Crosslinked olefin elastomer foam and elastomer composition therefor

ABSTRACT

A crosslinked olefin elastomer foam has a specific gravity of 0.05 to 0.2, an expansion ratio of 8 to 15, a compression set of 30 to 60% and a tear strength of 1.5 to 2.5 kg/cm. The crosslinked foam is obtained by heating an elastomer composition comprising a specific ethylene/α-olefin copolymer, an organic peroxide, a crosslinking auxiliary and a foaming agent. The crosslinked foam has a high expansion ratio, is free from surface roughening attributed to defoaming, realizes a soft touch, exhibits a low compression set and is excellent in mechanical strength (particularly tear strength) and heat resistance.

FIELD OF THE INVENTION

[0001] The present invention relates to a crosslinked olefin elastomerfoam and an elastomer composition therefor. More particularly, thepresent invention is concerned with a crosslinked olefin elastomer foamwhich realizes a soft touch, exhibits a low compression set and isexcellent in tear strength property and heat resistance, and isconcerned with an elastomer composition for the crosslinked foam.

BACKGROUND OF THE INVENTION

[0002] A wide variety of foams are commonly produced on a commercialscale and marketed. Foams of vulcanized rubbers and soft olefin plasticscan be mentioned as typical examples of such foams.

[0003] However, the conventional vulcanized rubbers, although havingexcellent flexibility and elasticity, inevitably require atime-consuming crosslinking or vulcanization step for realizing theseproperties, which incurs high cost. On the other hand, it is known touse soft olefin plastics, for example, thermoplastic resins such asethylene/vinyl acetate copolymer (EVA) and low-density polyethylene inthe formation of foams. These soft olefin plastics are basicallyinferior in heat resistance to the vulcanized rubbers. Thus, theyencounter problems such that the applicability of obtained foams isextremely limited and that defoaming is likely to occur because of poortension at melting to thereby render the expansion ratio low, whichdefoaming results in apparent surface roughening. Further, in the use ofEVA, an increase of vinyl acetate content enhances the tear strength andadherence thereof but deteriorates the abrasion resistance, surfacehardness and cell denseness. Therefore, the balance of properties isdifficult with the use of EVA. Still further, the specific gravity ofEVA itself is high, so that there occurs a problem such that foams ofdesirably low specific gravity cannot necessarily be obtained.

[0004] Therefore, there is a demand for the development of a crosslinkedolefin elastomer foam which has a high expansion ratio, is free fromsurface roughening attributed to defoaming, realizes a soft touch,exhibits a low compression set and is excellent in tear strengthproperty and heat resistance, and the development of an elastomercomposition for such a crosslinked foam.

OBJECT OF THE INVENTION

[0005] The present invention has been made with a view toward solvingthe above problems of the prior art. It is an object of the presentinvention to provide a crosslinked olefin elastomer foam which has ahigh expansion ratio, is free from surface roughening attributed todefoaming, realizes a soft touch, exhibits a low compression set and isexcellent in tear strength property and heat resistance. It is anotherobject of the present invention to provide an elastomer composition forsuch a crosslinked foam.

SUMMARY OF THE INVENTION

[0006] The first crosslinked olefin elastomer foam of the presentinvention has a specific gravity of 0.05 to 0.2, an expansion ratio of 8to 15, a compression set of 30 to 60% and a tear strength of 1.5 to 2.5kg/cm.

[0007] Another crosslinked olefin elastomer foam of the presentinvention has a specific gravity of 0.1 to 0.2, a compression set of 20to 60% and a tear strength of 2.0 to 4.0 kg/cm. This crosslinked foam isa secondarily compressed crosslinked foam obtained by subjecting thefirst crosslinked olefin elastomer foam of the present invention tofurther compression molding.

[0008] The first crosslinked olefin elastomer foam of the presentinvention can be a crosslinked foam obtained by heating an olefinelastomer composition, the olefin elastomer composition comprising:

[0009] an ethylene/α-olefin copolymer (A) having a density of 0.88 to0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min;

[0010] an organic peroxide (D);

[0011] a crosslinking auxiliary (E); and

[0012] a foaming agent (F).

[0013] The above ethylene/α-olefin copolymer (A) preferably has amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0.

[0014] The first crosslinked olefin elastomer foam of the presentinvention is preferably produced from a composition wherein theethylene/α-olefin copolymer (A) comprises a mixture of:

[0015] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min; and

[0016] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of (0.90 to 0.93 g/cm³ and a melt flow rate (measuredat 190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of0.1 to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A1) and ethylene/α-olefin copolymer (A2) is 100 parts by weight,

[0017] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0018] The first crosslinked olefin elastomer foam of the presentinvention is also preferably produced from a composition wherein theethylene/α-olefin copolymer (A) comprises a mixture of:

[0019] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A3)having a density of 0.88 to less than 0.91 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 50 g/10 min; and

[0020] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A4)having a density of 0.91 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A3) and ethylene/α-olefin copolymer (A4) is 100 parts by weight,

[0021] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0022] The α-olefin for forming the ethylene/α-olefin copolymers (A),(A1), (A2), (A3) and (A4) is preferably at least one member selectedfrom the group consisting of propylene, 1-butene, 1-hexene and 1-octene.

[0023] The crosslinking auxiliary (E) for use in this invention ispreferably triallyl isocyanurate (TAIC) or triallyl cyanurate (TAC).

[0024] In this invention, it is preferred that the crosslinkingauxiliary (E) and the organic peroxide (D) be used in a weight ratio((E)/(D)) of 1/8 to 3/1.

[0025] An organic or inorganic heat decomposable foaming agent ispreferably used as the above foaming agent (F).

[0026] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0027] an ethylene/α-olefin copolymer (A) having a density of 0.88 to0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min;

[0028] an organic peroxide (D);

[0029] a crosslinking auxiliary (E); and

[0030] a foaming agent (F).

[0031] It is preferred that the ethylene/α-olefin copolymer (A) have amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0.

[0032] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention is preferably a compositioncomprising:

[0033] an ethylene/α-olefin copolymer (A) having a density of 0.88 to0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min;

[0034] an organic peroxide (D);

[0035] a crosslinking auxiliary (E); and

[0036] a foaming agent (F),

[0037] wherein the ethylene/α-olefin copolymer (A) comprises a mixtureof:

[0038] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min; and

[0039] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A1) and ethylene/(-olefin copolymer (A2) is 100 parts by weight,

[0040] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0041] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention is also preferably a compositioncomprising:

[0042] an ethylene/α-olefin copolymer (A) having a density of 0.88 to0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min;

[0043] an organic peroxide (D);

[0044] a crosslinking auxiliary (E); and

[0045] a foaming agent (F), wherein the ethylene/α-olefin copolymer (A)comprises a mixture of:

[0046] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A3)having a density of 0.88 to less than 0.91 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 50 g/10 min; and

[0047] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A4)having a density of 0.91 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A3) and ethylene/α-olefin copolymer (A4) is 100 parts by weight,

[0048] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0049] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention enables preparation of thecrosslinked foam having a specific gravity of 0.05 to 0.2, an expansionratio of 8 to 15, a compression set of 30 to 60% and a tear strength of1.5 to 2.5 kg/cm.

[0050] The second crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0051] 70 to 95 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min, and

[0052] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, provided that the sum of ethylene/α-olefin copolymer(A) and modified polyolefin (B) is 100 parts by weight;

[0053] an organic peroxide (D);

[0054] a crosslinking auxiliary (E); and

[0055] a foaming agent (F).

[0056] It is preferred that the ethylene/α-olefin copolymer (A) have amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0.

[0057] The second crosslinked olefin elastomer foam of the presentinvention is preferably obtained from the composition wherein theethylene/α-olefin copolymer (A) comprises a mixture of:

[0058] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min, and

[0059] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A1) and ethylene/α-olefin copolymer (A2) is 100 parts by weight,

[0060] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0061] The third crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0062] 50 to 95 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min, and

[0063] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A) and high-pressure processedlow-density polyethylene (C) is 100 parts by weight;

[0064] an organic peroxide (D);

[0065] a crosslinking auxiliary (E); and

[0066] a foaming agent (F).

[0067] The fourth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0068] 5 to 90 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min,

[0069] 5 to 90 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, and

[0070] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2) and high-pressure processed low-density polyethylene (C) is 100parts by weight;

[0071] an organic peroxide (D);

[0072] a crosslinking auxiliary (E); and

[0073] a foaming agent (F),

[0074] wherein the ethylene/α-olefin copolymer (A1) and theethylene/α-olefin copolymer (A2) constitute a mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.

[0075] The fifth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0076] 20 to 90 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min,

[0077] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, and

[0078] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A), modified polyolefin (B) andhigh-pressure processed low-density polyethylene (C) is 100 parts byweight;

[0079] an organic peroxide (D);

[0080] a crosslinking auxiliary (E); and

[0081] a foaming agent (F).

[0082] The sixth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0083] 5 to 85 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min,

[0084] 5 to 85 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min,

[0085] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, and

[0086] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight;

[0087] an organic peroxide (D);

[0088] a crosslinking auxiliary (E); and

[0089] a foaming agent (F),

[0090] wherein the ethylene/α-olefin copolymer (A1) and theethylene/α-olefin copolymer (A2) constitute a mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.

[0091] The α-olefin for forming the ethylene/α-olefin copolymers (A),(A1) and (A2) is preferably at least one member selected from the groupconsisting of propylene, 1-butene, 1-hexene and 1-octene.

[0092] The crosslinking auxiliary (E) for use in this invention ispreferably triallyl isocyanurate (TAIC) or triallyl cyanurate (TAC).

[0093] In this invention, the crosslinking auxiliary (E) and the organicperoxide (D) are preferably used in a weight ratio ((E)/(D)) of 1/8 to3/1.

[0094] The second elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0095] 70 to 95 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min, and

[0096] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, provided that the sum of ethylene/α-olefin copolymer(A) and modified polyolefin (B) is 100 parts by weight;

[0097] an organic peroxide (D);

[0098] a crosslinking auxiliary (E); and

[0099] a foaming agent (F).

[0100] The second elastomer composition for crosslinked olefin elastomerfoam according to the present invention enables producing thecrosslinked foam having a low specific gravity and being excellent incompression set, mechanical strength (particularly tear strength) andadhesive strength.

[0101] It is preferred that the ethylene/α-olefin copolymer (A) have amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0.

[0102] The above ethylene/α-olefin copolymer (A) preferably comprises amixture of:

[0103] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min, and

[0104] 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A1) and ethylene/α-olefin copolymer (A2) is 100 parts by weight,

[0105] the mixture having a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0106] The use of the mixture of the ethylene/α-olefin copolymers (A1)and (A2) as the ethylene/α-olefin copolymer (A) in the second elastomercomposition enables producing a crosslinked foam having a low specificgravity and-being excellent in compression set, mechanical strength(particularly tear strength) and adhesive strength and high in hardness.

[0107] The third elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0108] 50 to 95 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min, and

[0109] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A) and high-pressure processedlow-density polyethylene (C) is 100 parts by weight;

[0110] an organic peroxide (D);

[0111] a crosslinking auxiliary (E); and

[0112] a foaming agent (F).

[0113] The third elastomer composition for crosslinked olefin elastomerfoam according to the present invention enables producing thecrosslinked foam having a low specific gravity and being excellent incompression set and mechanical strength (particularly tear strength) andhigh in hardness.

[0114] The fourth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0115] 5 to 90 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min,

[0116] 5 to 90 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, and

[0117] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2) and high-pressure processed low-density polyethylene (C) is 100parts by weight;

[0118] an organic peroxide (D);

[0119] a crosslinking auxiliary (E); and

[0120] a foaming agent (F),

[0121] wherein the ethylene/α-olefin copolymer (A1) and theethylene/α-olefin copolymer (A2) constitute a mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.

[0122] The fourth elastomer composition for crosslinked olefin elastomerfoam according to the present invention enables producing thecrosslinked foam having a low specific gravity and being excellent incompression set and mechanical strength (particularly tear strength) andhigh in hardness.

[0123] The fifth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0124] 20 to 90 parts by weight of an ethylene/α-olefin copolymer (A)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 10 g/10 min,

[0125] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, and

[0126] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A), modified polyolefin (B) andhigh-pressure processed low-density polyethylene (C) is 100 parts byweight;

[0127] an organic peroxide (D);

[0128] a crosslinking auxiliary (E); and

[0129] a foaming agent (F).

[0130] The fifth elastomer composition for crosslinked olefin elastomerfoam according to the present invention enables producing thecrosslinked foam having a low specific gravity and being excellent incompression set, mechanical strength (particularly tear strength) andadhesive strength and high in hardness.

[0131] The sixth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises:

[0132] 5 to 85 parts by weight of an ethylene/α-olefin copolymer (A1)having a density of greater than 0.88 g/cm³ but not greater than 0.90g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min,

[0133] 5 to 85 parts by weight of an ethylene/α-olefin copolymer (A2)having a density of 0.90 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min,

[0134] 5 to 30 parts by weight of a modified polyolefin (B) obtained bygrafting a polyolefin with an unsaturated carboxylic acid or aderivative thereof, and

[0135] 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight;

[0136] an organic peroxide (D);

[0137] a crosslinking auxiliary (E); and

[0138] a foaming agent (F),

[0139] wherein the ethylene/α-olefin copolymer (A1) and theethylene/α-olefin copolymer (A2) constitute a mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.

[0140] The sixth elastomer composition for corsslinked olefin elastomerfoam according to the present invention enables producing thecrosslinked foam having a low specific gravity and being excellent incompression set, mechanical strength (particularly tear strength) andadhesive strength and high in hardness.

[0141] In this invention, the crosslinking auxiliary (E) and the organicperoxide (D) are preferably used in a weight ratio ((E)/(D)) of 1/8 to3/1.

[0142] The second, third, fourth, fifth and sixth elastomer compositionsfor crosslinked olefin elastomer foam according to the present inventionenable preparation of the crosslinked foam having a specific gravity of0.05 to 0.2, an expansion ratio of 8 to 15, a compression set of 30 to60% and a tear strength of 1.5 to 2.5 kg/cm.

[0143] Further compression molding of the second, third, fourth, fifthand sixth crosslinked olefin elastomer foams according to the presentinvention enables preparation of the secondarily compressed crosslinkedfoam having a specific gravity of 0.1 to 0.2, a compression set of 20 to60% and a tear strength of 2.0 to 4.0 kg/cm.

[0144] The seventh crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising:

[0145] 70 to 98 parts by weight of an ethylene/α-olefin copolymer (G)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, and

[0146] 2 to 30 parts by weight of a polypropylene (H) having a melt flowrate (measured at 230° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 50 g/10 min, provided that the sum ofethylene/α-olefin copolymer (G) and polypropylene (H) is 100 parts byweight;

[0147] an organic peroxide (D);

[0148] a crosslinking auxiliary (E); and

[0149] a foaming agent (F),

[0150] wherein the ethylene/α-olefin copolymer (G) and the polypropylene(H) constitute a mixture having a melt flow rate (measured at 230° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 10g/10 min.

[0151] The polypropylene (H) can be at least one member selected fromthe group consisting of propylene homopolymer, propylene blockcopolymers and propylene/α-olefin random copolymers.

[0152] The α-olefin for forming the propylene/α-olefin random copolymeris preferably at least one member selected from the group consisting ofethylene, 1-butene, 1-hexene and 1-octene.

[0153] The crosslinking auxiliary (E) for use in this invention ispreferably triallyl isocyanurate (TAIC) or triallyl cyanurate (TAC).

[0154] In this invention, the crosslinking auxiliary (E) and the organicperoxide (D) are preferably used in a weight ratio ((E)/(D)) of 1/8 to3/1.

[0155] An organic or inorganic heat decomposable foaming-agent ispreferably used as the above foaming agent (F).

[0156] The seventh elastomer composition for crosslinked olefinelastomer foam according to the present invention comprises:

[0157] 70 to 98 parts by weight of an ethylene/α-olefin copolymer (G)having a density of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, and

[0158] 2 to 30 parts by weight of a polypropylene (H) having a melt flowrate (measured at 230° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 50 g/10 min, provided that the sum ofethylene/α-olefin copolymer (G) and polypropylene (H) is 100 parts byweight;

[0159] an organic peroxide (D);

[0160] a crosslinking auxiliary (E); and

[0161] a foaming agent (F),

[0162] wherein the ethylene/α-olefin copolymer (G) and the polypropylene(H) constitute a mixture having a melt flow rate (measured at 230° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 10g/10 min.

[0163] The seventh elastomer composition for crosslinked olefinelastomer foam according to the present invention enables preparation ofthe crosslinked foam having a specific gravity of 0.05 to 0.2, anexpansion ratio of 8 to 15, a compression set of 30 to 60% and a tearstrength of 1.5 to 2.5 kg/cm.

[0164] Further compression molding of this crosslinked foam enablespreparation of the secondarily compressed crosslinked foam having aspecific gravity of 0.1 to 0.2, a compression set of 20 to 60% and atear strength of 2.0 to 4.0 kg/cm.

DETAILED DESCRIPTION OF THE INVENTION

[0165] The crosslinked olefin elastomer foams and elastomer compositionstherefor according to the present invention will be described in detailbelow.

[0166] Now, the first crosslinked olefin elastomer foam and elastomercomposition therefor according to the present invention will bedescribed in detail.

[0167] First Crosslinked Foam

[0168] The first crosslinked olefin elastomer foam of the presentinvention has a specific gravity (JIS K 7112) of 0.05 to 0.2, anexpansion ratio of 8 to 15, a compression set (JIS K 6301) of 30 to 60%and a tear strength (BS5131-2.6) of 1.5 to 2.5 kg/cm. The firstcrosslinked olefin elastomer foam of the present invention whichpossesses these characteristics has an appropriate crosslink structure,realizes a soft touch, has a high expansion ratio and a low specificgravity, is free from surface roughening attributed to defoaming,exhibits a low compression set and is excellent in tear strengthproperty and heat resistance.

[0169] The other crosslinked olefin elastomer foam of the presentinvention has a specific gravity of 0.1 to 0.2, a compression set of 20to 60% and a tear strength of 2.0 to 4.0 kg/cm. This crosslinked foam isa secondarily compressed crosslinked foam obtained by subjecting thefirst crosslinked olefin elastomer foam of the present invention tofurther compression molding.

[0170] It is preferred that the crosslinked foam and secondarilycompressed crosslinked foam be prepared from the first elastomercomposition for crosslinked olefin elastomer foam according to thepresent invention.

[0171] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention is a composition not crosslinkedand not foamed which is crosslinked and foamed upon being heated atgiven temperature or over. It comprises a specified ethylene/α-olefincopolymer (A), an organic peroxide (D), a crosslinking auxiliary (E) anda foaming agent (F).

[0172] Ethylene/α-olefin Copolymer (A)

[0173] The ethylene/α-olefin copolymer (A) for use in the presentinvention is an amorphous or lowly crystalline random copolymer preparedfrom ethylene and an α-olefin having 3 to 20 carbon atoms. It ispreferably a soft ethylene/α-olefin copolymer having a density (ASTM D1505) of 0.88 to 0.92 g/cm³ and a melt flow rate (MFR measured at 190°C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 10g/10 min, especially 0.5 to 10 g/10 min.

[0174] It is preferred that the ethylene/α-olefin copolymer (A) have amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0. The use of the ethylene/α-olefincopolymer (A) whose molecular weight distribution (Mw/Mn) falls withinthe above range enables preparation of an elastomer composition fromwhich a crosslinked elastomer foam having a low specific gravity (highexpansion) and excellent compression set can be produced.

[0175] The above molecular weight distribution (Mw/Mn) is measured bythe use of GPC-150C manufactured by Millipore under the followingconditions.

[0176] Measurement is performed under the conditions such that TSK GNHHT is used as a separation column, the column size is 72 mm diameter and600 mm length, the column temperature is 140° C., o-dichlorobenzene(produced by Wako Pure Chemical Industries, Ltd.) and 0.025 wt. % BHT(produced by Takeda Chemical Industries, Ltd.) are used as a mobilephase and an antioxidant, respectively, the moving velocity is 1.0ml/min, the sample concentration and the quantity of sample injected are0.1 wt. % and 500 microliters, respectively, and a differentialrefractometer is used as the detector. Standard polystyrene formolecular weight Mw<1000 and Mw>4×10⁶ is one produced by TosohCorporation while standard polystyrene for 1000≦Mw≦4×10⁶ is one producedby Pressure Chemical.

[0177] The α-olefin copolymerized with ethylene can be selected fromamong α-olefins having 3 to 20 carbon atoms, examples of which includepropylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 1-undecene, 1-dodecene, 1-hexadecene, 1-octadecene,1-nonadecene, 1-eicosene and 4-methyl-1-pentene. Of these, α-olefinshaving 3 to 10 carbon atoms are preferred. Propylene, 1-butene, 1-hexeneand 1-octene are especially preferred. These α-olefins can be usedeither individually or in combination.

[0178] It is preferred that the above ethylene/α-olefin copolymer (A)contain units derived from ethylene in an amount of 85 to 98 mol % andunits derived from α-olefins having 3 to 20 carbon atoms in an amount of2 to 15 mol %.

[0179] The composition of the ethylene/α-olefin copolymer (A) isgenerally determined by homogeneously dissolving about 200 mg of thecopolymer in 1 ml of hexachlorobutadiene in a sample tube of 10 mmdiameter to thereby obtain a sample solution and subjecting the samplesolution to ¹³C-NMR spectroscopy under the conditions such that themeasuring temperature is 120° C., the measuring frequency 25.05 MHz, thespectrum width 1500 Hz, the pulse cycle time 4.2 sec and the pulse width6 μsec.

[0180] Furthermore, the ethylene/α-olefin copolymer (A) may containunits derived from other polymerizable monomers than the above monomersto an extent such that the object of the present invention is notdeparted from.

[0181] Examples of suitable ethylene/α-olefin copolymers (A) includeethylene/propylene random copolymer, ethylene/1-butene random copolymer,ethylene/propylene/1-butene random copolymer,ethylene/propylene/ethylidenenorbornene random copolymer,ethylene/1-hexene random copolymer and ethylene/1-octene randomcopolymer. Of these, ethylene/propylene random copolymer,ethylene/1-butene random copolymer, ethylene/1-hexene random copolymerand ethylene/1-octene random copolymer are preferred. These copolymersmay be used in combination.

[0182] The use of linear ethylene/α-olefin copolymer exhibiting anintrinsic viscosity ratio (gη*) of greater than 0.95 is advantageous inthat the final foam molding exhibits a low shrinkage ratio. Theintrinsic viscosity ratio (gη*) is calculated by the formula:

gη*=(η)/(η)_(blank)

[0183] wherein:

[0184] (η): intrinsic viscosity of the copolymer as measured in decalinat 135° C., and

[0185] (η)_(blank): intrinsic viscosity of linear ethylene/α-olefincopolymer of 70 mol % ethylene content having the same weight averagemolecular weight (measured by light scattering).

[0186] In this connection, reference is made to Japanese PatentPublication No. 3(1991)-14045.

[0187] On the other hand, the use of long-chain branchedethylene/α-olefin copolymer exhibiting a gη* value of 0.2 to 0.95realizes a desirable fluidity and a high melt tension to thereby ensureexcellent moldability and also realizes a high expansion ratio and anexcellent compression set.

[0188] As preferable ethylene/α-olefin copolymer (A), there can bementioned:

[0189] a mixture of the following ethylene/α-olefin copolymers (A1) and(A2), the mixture exhibiting a melt flow rate (measured at 190° C. undera load of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min,or

[0190] a mixture of the following ethylene/α-olefin copolymers (A3) and(A4), the mixture exhibiting a melt flow rate (measured at 190° C. undera load of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.

[0191] It is preferred that each of the mixture of ethylene/α-olefincopolymers (A1) and (A2) and the mixture of ethylene/α-olefin copolymers(A3) and (A4) have a molecular weight distribution (Mw/Mn), as measuredby gel permeation chromatography (GPC), of 2.3 to 4.0. The use of themixture of ethylene/α-olefin copolymers (A1) and (A2) whose molecularweight distribution (Mw/Mn) falls within the above range or the mixtureof ethylene/α-olefin copolymers (A3) and (A4) whose molecular weightdistribution (Mw/Mn) falls within the above range enables preparation ofan elastomer composition from which a crosslinked elastomer foam havinga low specific gravity (high expansion) and being excellent incompression set can be produced.

[0192] The ethylene/α-olefin copolymer (A1) is an amorphous or lowlycrystalline random copolymer prepared from ethylene and an α-olefinhaving 3 to 20 carbon atoms. It is preferably a soft ethylene/α-olefincopolymer having a density (ASTM D 1505) of greater than 0.88 g/cm³ butnot greater than 0.90 g/cm³ and a melt flow rate (MFR measured at 190°C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50g/10 min, especially 0.5 to 20 g/10 min.

[0193] It is preferred that the ethylene/α-olefin copolymer (A1) containunits derived from ethylene in an amount of 85 to 93 mol % and unitsderived from α-olefins having 3 to 20 carbon atoms in an amount of 7 to15 mol %.

[0194] The ethylene/α-olefin copolymer (A1) generally has acrystallinity, as measured by X-ray diffractometry, of 40% or below,preferably 10 to 30%.

[0195] This ethylene/α-olefin copolymer (A1) can be produced by theconventional process in which use is made of a vanadium catalyst, atitanium catalyst, a metallocene catalyst or the like.

[0196] The ethylene/α-olefin copolymer (A2) is an amorphous or lowlycrystalline random copolymer prepared from ethylene and an α-olefinhaving 3 to 20 carbon atoms. It is preferably a soft ethylene/α-olefincopolymer having a density (ASTM D 1505) of 0.90 to 0.93 g/cm³,especially 0.91 to 0.92 g/cm³, and a melt flow rate (MFR measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, especially 0.5 to 20 g/10 min.

[0197] It is preferred that the ethylene/α-olefin copolymer (A2) containunits derived from ethylene in an amount of 93 to 98 mol % and unitsderived from α-olefins having 3 to 20 carbon atoms in an amount of 2 to7 mol %.

[0198] This ethylene/α-olefin copolymer (A2) can be produced by theconventional process in which use is made of a Ziegler catalyst, ametallocene catalyst or the like.

[0199] The ethylene/α-olefin copolymer (A1) is used in an amount of 5 to95 parts by weight, preferably 50 to 90 parts by weight, while theethylene/α-olefin copolymer (A2) is used in an amount of 5 to 95 partsby weight, preferably 10 to 50 parts by weight, provided that the sum ofethylene/α-olefin copolymer (A1) and ethylene/α-olefin copolymer (A2) is100 parts by weight.

[0200] The use of a long-chain branched ethylene/α-olefin copolymerwhose gη* value is in the range of 0.2 to 0.95 as either of theethylene/α-olefin copolymers (A1) and (A2) leads to an increasedexpansion ratio and enables preparation of an elastomer composition fromwhich a crosslinked elastomer foam excellent in compression set can beproduced.

[0201] The gη* value can be determined by the method described inJapanese Patent Publication No. 3(1991)-14045. Ethylene/α-olefincopolymers whose gη* value is greater than 0.95 but not greater than 1.0are linear. In particular, when the gη* value is in the range of 0.2 to0.95, the ethylene/α-olefin copolymer is a relatively-long-chainbranched copolymer.

[0202] The ethylene/α-olefin copolymer (A3) is an amorphous or lowlycrystalline random copolymer prepared from ethylene and an α-olefinhaving 3 to 20 carbon atoms. It is preferably a soft ethylene/α-olefincopolymer having a density (ASTM D 1505) of 0.88 to less than 0.91 g/cm³and a melt flow rate (MFR measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, especially 0.5 to 20g/10 min.

[0203] It is preferred that the ethylene/α-olefin copolymer (A3) containunits derived from ethylene in an amount of 85 to 93 mol % and unitsderived from α-olefins having 3 to 20 carbon atoms in an amount of 7 to15 mol %.

[0204] The ethylene/α-olefin copolymer (A3) generally has acrystallinity, as measured by X-ray diffractometry, of 40% or below,preferably 10 to 30%.

[0205] This ethylene/α-olefin copolymer (A3) can be produced by theconventional process in which use is made of a vanadium catalyst, atitanium catalyst, a metallocene catalyst or the like.

[0206] The ethylene/α-olefin copolymer (A4) is an amorphous or lowlycrystalline random copolymer prepared from ethylene and an α-olefinhaving 3 to 20 carbon atoms. It is preferably a soft ethylene/α-olefincopolymer having a density (ASTM D 1505) of 0.91 to 0.93 g/cm³,especially 0.91 to 0.92 g/cm³, and a melt flow rate (MFR measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, especially 0.5 to 20 g/10 min.

[0207] It is preferred that the ethylene/α-olefin copolymer (A4) containunits derived from ethylene in an amount of 93 to 98 mol % and unitsderived from α-olefins having 3 to 20 carbon atoms in an amount of 2 to7 mol %.

[0208] This ethylene/α-olefin copolymer (A4) can be produced by theconventional process in which use is made of a Ziegler catalyst, ametallocene catalyst or the like.

[0209] The ethylene/α-olefin copolymer (A3) is used in an amount of 5 to95 parts by weight, preferably 50 to 90 parts by weight, while theethylene/(-olefin copolymer (A4) is used in an amount of 5 to 95 partsby weight, preferably 10 to 50 parts by weight, provided that the sum ofethylene/α-olefin copolymer (A3) and ethylene/α-olefin copolymer (A4) is100 parts by weight.

[0210] The use of a long-chain branched ethylene/α-olefin copolymerwhose gη* value is in the range of 0.2 to 0.95 as either of theethylene/α-olefin copolymers (A3) and (A4) leads to an increasedexpansion ratio and enables preparation of an elastomer composition fromwhich a crosslinked elastomer foam excellent in compression set can beproduced.

[0211] Organic Peroxide (D)

[0212] The organic peroxide (D) for use as a crosslinking agent in thepresent invention can be selected from among, for example, dicumylperoxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,1,3-bis(t-butylperoxyisopropyl)benzene,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,n-butyl-4,4-bis(t-butylperoxy) valerate, benzoyl peroxide,p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butyl perbenzoate, t-butyl peroxyisopropyl carbonate,diacetyl peroxide, lauroyl peroxide and t-butyl cumyl peroxide.

[0213] In the present invention, the organic peroxide (D) is generallyused in an amount of 0.1 to 1.5 parts by weight, preferably 0.2 to 1.0part by weight, per 100 parts by weight of ethylene/α-olefin copolymer(A). The use of the organic peroxide (D), together with a crosslinkingauxiliary (E), in the above amount enables obtaining a crosslinked foamwith an appropriate crosslink structure.

[0214] Crosslinking Auxiliary (E)

[0215] The crosslinking auxiliary (E) for use in the present inventioncan be selected from among, for example, peroxy crosslinking auxiliariessuch as sulfur, p-quinone dioxime, p,p′-dibenzoylquinone dioxime,N-methyl-N-4-dinitrosoaniline, nitrosobenzene, diphenylguanidine andtrimethylolpropane-N,N′-m-phenylenedimaleimide; divinylbenzene, triallylcyanurate (TAC) and triallyl isocyanurate (TAIC); polyfunctionalmethacrylate monomers such as ethylene glycol dimethacrylate, diethyleneglycol dimethacrylate, polyethylene glycol dimethacrylate,trimethylolpropane trimethacrylate and allyl methacrylate; andpolyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate.Of these, triallyl cyanurate (TAC) and triallyl isocyanurate (TAIC) arepreferred.

[0216] In the present invention, the above crosslinking auxiliary (E) ispreferably used at a weight ratio of crosslinking auxiliary (E) toorganic peroxide (D) ((E)/(D)) of 1/10 to 5/1, still preferably 1/8 to3/1, and optimally 1/5 to 2/1.

[0217] Foaming Agent (F)

[0218] The foaming agent (F) for use in the present invention can beselected from among, for example, organic heat decomposable foamingagents such as azodicarbonamide (ADCA),N,N′-dinitrosopentamethylenetetramine,4,4′-oxybis(benzenesulfonylhydrazide),diphenylsulfone-3,3′-disulfonylhydrazide, p-toluenesulfonylsemicarbazideand trihydrazinotriazine; and inorganic heat decomposable foaming agentssuch as sodium hydrogencarbonate, sodium carbonate, ammoniumhydrogencarbonate and ammonium carbonate. Of these, azodicarbonamide(ADCA) and sodium hydrogencarbonate are especially preferred.

[0219] In the present invention, the foaming agent (F) is generally usedin an amount of 3 to 20 parts by weight, preferably 5 to 15 parts byweight, per 100 parts by weight of ethylene/α-olefin copolymer (A). Theuse of the foaming agent (F) in the above amount enables obtaining afoam molding whose expansion ratio and closed cell ratio are high. Theamount of foaming agent (F) used is decided taking into account theexpansion ratio of crosslinked foam.

[0220] Production of First Elastomer Composition

[0221] The first elastomer composition for crosslinked olefin elastomerfoam according to the present invention is a noncrosslinked nonfoamedcomposition, which may be in molten form or in the form of pellets or asheet obtained by cooling the melt to effect solidification.

[0222] Pellets of the first elastomer composition of the presentinvention can be produced by, for example, mixing together the aboveethylene/α-olefin copolymer (A), organic peroxide (D), crosslinkingauxiliary (E) and foaming agent (F) in the above amounts by means ofHenschel mixer or the like, and melting and plasticizing the mixture bymeans of a blender such as a banbury mixer, an extruder or the like atsuch a temperature that the foaming agent (F) and organic peroxide (D)are not decomposed to thereby effect homogeneous mixing and dispersion,followed by pelletization by means of a pelletizer.

[0223] This composition can optionally be loaded with various additivessuch as a filler, a heat stabilizer, a weathering stabilizer, a flameretarder, a hydrochloric acid absorber and a pigment in addition to theabove components to an extent such that the object of the presentinvention is not departed from.

[0224] On the other hand, a sheet of the first elastomer composition ofthe present invention can be produced by, for example, sheeting theabove obtained pellets of the composition by the use of an extruder or acalendering machine. Alternatively, the foamable sheet in thenoncrosslinked and nonfoamed state can be produced by blending togethercomposition components by means of, for example, Brabender Plastographand, thereafter, sheeting the blend by means of calender rolls or apress molding machine. Furthermore, the foamable sheet can be producedby blending composition components by means of an extruder and,thereafter, sheeting the blend through T dies or annular dies.

[0225] Production of First Crosslinked Olefin Elastomer Foam

[0226] The first crosslinked olefin elastomer foam of the presentinvention can be produced by, for example, the following procedure.

[0227] Crosslinked foam can be obtained by feeding a given amount of thethus obtained noncrosslinked nonfoamed composition sheet into a pressuremolding metal mold heated at 160 to 175° C., melting the sheet underpressure to thereby effect a crosslinking reaction and decomposition ofthe foaming agent (F), and opening the pressure molding metal mold tothereby foam the composition.

[0228] With respect to the pressured crosslinking foaming moldingconditions in the pressure molding metal mold, the metal moldtemperature must not be lower than the decomposition temperature of thefoaming agent (F). It is preferred that the metal mold temperature benot lower than the melting temperature of the composition but onepermitting high melt viscosity at the time of foaming, that is, 165 to175° C.

[0229] The intra-cavity configuration of the pressure molding metalmold, although not particularly limited, is generally such that a platecan be obtained. The pressure molding metal mold must have a structurecapable of complete sealing for preventing the leakage of molten resinto outside. Also, use can be made of a frame having a structure capableof complete sealing for preventing the leakage of molten resin tooutside. It is preferred from the viewpoint of resin release easinessthat the frame have its inner side tapered.

[0230] The pressure applied at the pressured melting is generally 50kg/cm² or over, preferably 100 to 200 kg/cm².

[0231] The heating period under pressure, although changed depending onthe amount of composition fed into the pressure molding metal mold, mustbe sufficient to cause the composition to melt, reach 165 to 175° C. andundergo a crosslinking reaction and decomposition of the foaming agent(F). The time required for the crosslinking reaction and decompositionof the foaming agent (F), although depending on the temperature, must beat least 10 min.

[0232] Opening the pressure molding metal mold after the completion ofthe crosslinking reaction and decomposition of the foaming agent (F)causes a foaming to occur, so that a crosslinked foam can be obtained.

[0233] The process for producing a crosslinked olefin elastomer foam inwhich the cooling solidified pellets or sheet is used as thenoncrosslinked nonfoamed composition for feeding into the pressuremolding metal mold is advantageous in that, due to the pellet or sheetform, the noncrosslinked foamable composition has excellent storagestability and is free from time and space restraints.

[0234] On the other hand, in the process for producing a crosslinkedfoam in which the molten composition is used as the noncrosslinkedfoamable composition for feeding into the pressure molding metal mold,the step of re-heating the pellets or sheet to effect melting can beavoided, so that a crosslinked foam can be obtained within a shorterperiod.

[0235] Thereafter, the thus obtained hot crosslinked foam is immediatelytransferred into a cooling molding metal mold, in which, under pressure,molding and cooling are simultaneously carried out. Thus, a crosslinkedfoam is obtained.

[0236] The obtained crosslinked foam (hot foam), although its adherenceis low because of the crosslinking, must be disposed on, for example, aplate of less adherence and high releasability and immediatelytransferred into the cooling molding metal mold in order to achievemolding in the cooling molding metal mold.

[0237] The cooling molding metal mold is equipped with an embeddedcooling pipe for circulating, for example, water inside the coolingmolding metal mold. In the present invention, the cooling molding metalmold, although its structure is not particularly limited, generallycomprises an upper die and a lower die.

[0238] Any excess pressure application is not needed after thecompletion of crosslinked foam shaping. It is preferred that thepressure application be effected in conformity with the shrinkage offoam made by the cooling.

[0239] For obtaining a secondarily compressed crosslinked foam, the thusobtained crosslinked foam is shaved taking into account theconfiguration of molding metal mold and compression ratio, and theshaved crosslinked foam is transferred into a molding metal mold heatedat 150 to 175° C., preferably 155 to 165° C., in which molding underpressure is carried out.

[0240] The applied pressure is generally at least 50 kg/cm², preferablyin the range of 100 to 200 kg/cm². The heating period under pressure,although depending on the configuration and temperature of molding metalmold, is generally required to be at least 7 min.

[0241] Immediately after the completion of the heating, the moldingmetal mold with the foam accommodated in its cavity is cooled. Thus, asecondarily compressed crosslinked foam is obtained.

[0242] It is preferred that the thus obtained secondarily compressedcrosslinked foam have a specific gravity of 0.1 to 0.2, a compressionset of 20 to 60% and a tear strength of 2.0 to 4.0 kg/cm.

[0243] The second to sixth crosslinked olefin elastomer foams andelastomer compositions therefor according to the present invention willbe described in detail below.

[0244] Second to Sixth Crosslinked Foams

[0245] The second crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition comprising an ethylene/α-olefin copolymer (A), a modifiedpolyolefin (B), an organic peroxide (D), a crosslinking auxiliary (E)and a foaming agent (F). This ethylene/α-olefin copolymer (A) may be amixture of an ethylene/α-olefin copolymer (A1) and an ethylene/α-olefincopolymer (A2).

[0246] The third crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition comprising an ethylene/α-olefin copolymer (A), ahigh-pressure processed low-density polyethylene (C), an organicperoxide (D), a crosslinking auxiliary (E) and a foaming agent (F).

[0247] The fourth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition comprising an ethylene/α-olefin copolymer (A1), anethylene/α-olefin copolymer (A2), a high-pressure processed low-densitypolyethylene (C), an organic peroxide (D), a crosslinking auxiliary (E)and a foaming agent (F).

[0248] The fifth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition comprising an ethylene/α-olefin copolymer (A), a modifiedpolyolefin (B), a high-pressure processed low-density polyethylene (C),an organic peroxide (D), a crosslinking auxiliary (E) and a foamingagent (F).

[0249] The sixth crosslinked olefin elastomer foam of the presentinvention is a crosslinked foam obtained by heating an olefin elastomercomposition comprising an olefin elastomer composition comprising anethylene/α-olefin copolymer (A1), an ethylene/α-olefin copolymer (A2), amodified polyolefin (B), a high-pressure processed low-densitypolyethylene (C), an organic peroxide (D), a crosslinking auxiliary (E)and a foaming agent (F).

[0250] The second, third, fourth, fifth and sixth elastomer compositionsfor crosslinked olefin elastomer foams according to the presentinvention are noncrosslinked nonfoamed compositions which are used inthe preparation of the above second, third, fourth, fifth and sixthcrosslinked olefin elastomer foams of the present invention,respectively, and which are crosslinked and foamed when heated at giventemperature or higher.

[0251] The second elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises an ethylene/α-olefincopolymer (A) (or a mixture of an ethylene/α-olefin copolymer (A1) andan ethylene/α-olefin copolymer (A2)), a modified polyolefin (B), anorganic peroxide (D), a crosslinking auxiliary (E) and a foaming agent(F).

[0252] The third elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises an ethylene/α-olefincopolymer (A), a high-pressure processed low-density polyethylene (C),an organic peroxide (D), a crosslinking auxiliary (E) and a foamingagent (F).

[0253] The fourth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises an ethylene/α-olefincopolymer (A1), an ethylene/α-olefin copolymer (A2), a high-pressureprocessed low-density polyethylene (C), an organic peroxide (D), acrosslinking auxiliary (E) and a foaming agent (F).

[0254] The fifth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises an ethylene/α-olefincopolymer (A), a modified polyolefin (B), a high-pressure processedlow-density polyethylene (C), an organic peroxide (D), a crosslinkingauxiliary (E) and a foaming agent (F).

[0255] The sixth elastomer composition for crosslinked olefin elastomerfoam according to the present invention comprises an ethylene/α-olefincopolymer (A1), an ethylene/α-olefin copolymer (A2), a modifiedpolyolefin (B), a high-pressure processed low-density polyethylene (C),an organic peroxide (D), a crosslinking auxiliary (E) and a foamingagent (F).

[0256] (Ethylene/α-olefin Copolymer (A))

[0257] The ethylene/α-olefin copolymer (A) for use in the presentinvention is an amorphous or lowly crystalline random copolymer preparedfrom ethylene and an α-olefin having 3 to 20 carbon atoms. It is thesame as the ethylene/α-olefin copolymer (A) employed in the preparationof the above first crosslinked olefin elastomer foam and elastomercomposition therefor according to the present invention.

[0258] In the second elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A) is used in an amount of 70 to 95 parts by weight,preferably 80 to 95 parts by weight, and still preferably 85 to 95 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A) and modified polyolefin (B). The use of theethylene/α-olefin copolymer (A) in the above amounts enables preparationof an elastomer composition from which a crosslinked foam having a lowspecific gravity and being excellent in compression set, mechanicalstrength (particularly tear strength) and adhesive strength can beproduced.

[0259] In the second elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A1) is used in an amount of 5 to 95 parts by weight,preferably 50 to 90 parts by weight, and the ethylene/α-olefin copolymer(A2) is used in an amount of 5 to 95 parts by weight, preferably 10 to50 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A1) and ethylene/α-olefin copolymer (A2).The use of the ethylene/α-olefin copolymers (A1) and (A2) in the aboveamounts enables preparation of an elastomer composition from which acrosslinked foam having a low specific gravity and being excellent incompression set and mechanical strength (particularly tear strength) andhigh in hardness can be produced. In particular, the use of the abovelong-chain branched ethylene/α-olefin copolymer as either of theethylene/α-olefin copolymers (A1) and (A2) enables preparation of anelastomer composition from which a crosslinked elastomer foam having amuch lower specific gravity and excellent compression set can beproduced.

[0260] In the third elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A) is used in an amount of 50 to 95 parts by weight,preferably 60 to 90 parts by weight, and still preferably 70 to 85 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A) and high-pressure processed low-density polyethylene (C)The use of the ethylene/α-olefin copolymer (A) in the above amountsenables preparation of an elastomer composition from which a crosslinkedfoam having a low specific gravity (high expansion) and being excellentin compression set and mechanical strength (particularly tear strength)and high in hardness can be produced.

[0261] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A1) is used in an amount of 5 to 90 parts by weight,preferably 40 to 80 parts by weight, and still preferably 50 to 70 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A1), ethylene/α-olefin copolymer (A2) and high-pressureprocessed low-density polyethylene (C). The use of the ethylene/α-olefincopolymer (A1) in the above amounts enables preparation of an elastomercomposition from which a crosslinked foam having a low specific gravity(high expansion) and excellent compression set can be produced.

[0262] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A2) is used in an amount of 5 to 90 parts by weight,preferably 10 to 50 parts by weight, and still preferably 15 to 30 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A1), ethylene/α-olefin copolymer (A2) and high-pressureprocessed low-density polyethylene (C). The use of the ethylene/α-olefincopolymer (A2) in the above amounts enables preparation of an elastomercomposition from which a crosslinked foam having a high hardness andexcellent tear strength can be produced.

[0263] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, in particular, theuse of the above long-chain branched ethylene/α-olefin copolymer aseither of the ethylene/α-olefin copolymers (A1) and (A2) enablespreparation of an elastomer composition from which a crosslinkedelastomer foam having a much lower specific gravity (higher expansion)and excellent compression set can be produced.

[0264] In the fifth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A) is used in an amount of 20 to 90 parts by weight,preferably 50 to 80 parts by weight, and still preferably 60 to 80 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A), modified polyolefin (B) and high-pressure processedlow-density polyethylene (C). The use of the ethylene/α-olefin copolymer(A) in the above amounts enables preparation of an elastomer compositionfrom which a crosslinked foam having a low specific gravity (highexpansion) and excellent compression set can be produced.

[0265] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A1) is used in an amount of 5 to 85 parts by weight,preferably 35 to 75 parts by weight, and still preferably 50 to 65 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A1), ethylene/α-olefin copolymer (A2), modified polyolefin(B) and high-pressure processed low-density polyethylene (C). The use ofthe ethylene/α-olefin copolymer (A1) in the above amounts enablespreparation of an elastomer composition from which a crosslinked foamhaving a low specific gravity (high expansion) and excellent compressionset can be produced.

[0266] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the ethylene/α-olefincopolymer (A2) is used in an amount of 5 to 85 parts by weight,preferably 10 to 50 parts by weight, and still preferably 15 to 30 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A1), ethylene/α-olefin copolymer (A2), modified polyolefin(B) and high-pressure processed low-density polyethylene (C). The use ofthe ethylene/α-olefin copolymer (A2) in the above amounts enablespreparation of an elastomer composition from which a crosslinked foamhaving a high hardness and excellent tear strength can be produced.

[0267] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, in particular, theuse of the above long-chain branched ethylene/α-olefin copolymer aseither of the ethylene/α-olefin copolymers (A1) and (A2) enablespreparation of an elastomer composition from which a crosslinkedelastomer foam having a much lower specific gravity (higher expansion)and excellent compression set can be produced.

[0268] (Modified Polyolefin (B))

[0269] The modified polyolefin (B) for use in the present invention is agraft modification product obtained by grafting a polyolefin with anunsaturated carboxylic acid or a derivative thereof.

[0270] The polyolefin prior to graft modification for use in the presentinvention is preferably, for example, an ethylene/α-olefin randomcopolymer prepared from ethylene and an α-olefin having 3 to 20 carbonatoms.

[0271] The particular α-olefin having 3 to 20 carbon atoms can be thesame as aforementioned with respect to the formation ofethylene/α-olefin copolymer (A). In this invention, an α-olefin having 3to 10 carbon atoms is preferred. Especially, propylene, 1-butene,1-hexene and 1-octene are preferred. These α-olefins can be used eitherindividually or in combination.

[0272] The density (ASTM D 1505) of this ethylene/α-olefin randomcopolymer is in the range of 0.86 to 0.93 g/cm³, preferably 0.87 to 0.92g/cm³, and still preferably 0.88 to 0.92 g/cm³. The use of a modifiedethylene/α-olefin random copolymer obtained by grafting anethylene/α-olefin random copolymer whose density falls within the aboveranges with an unsaturated carboxylic acid or a derivative thereofenables preparation of an elastomer composition from which a crosslinkedelastomer foam excellent in tear strength and adhesion can be produced.

[0273] The melt flow rate (MFR measured at 190° C. under a load of 2.16kg in accordance with ASTM D 1238) of this unmodified ethylene/α-olefinrandom copolymer is in the range of 0.1 to 100 g/10 min, preferably 0.5to 50 g/10 min, and still preferably 0.5 to 20 g/10 min. The modifiedethylene/α-olefin random copolymer obtained from unmodifiedethylene/α-olefin random copolymer whose MFR falls within the aboveranges has excellent blendability with the ethylene/α-olefin copolymer(A). Further, the use of this modified ethylene/α-olefin randomcopolymer enables improvement of adhesive strength and mechanicalstrength.

[0274] The unmodified ethylene/α-olefin random copolymer generally has acrystallinity, as measured by X-ray diffractometry, of 40% or below,preferably 10 to 30%. The use of the modified ethylene/α-olefin randomcopolymer obtained from unmodified ethylene/α-olefin random copolymerwhose crystallinity is 40% or below enables preparation of an elastomercomposition having excellent impact resistance.

[0275] The unmodified ethylene/α-olefin random copolymer having theabove properties can be produced by the customary copolymerizationmethod, in which random copolymerization of ethylene and an α-olefinhaving 3 to 20 carbon atoms is performed in the presence of, forexample, a vanadium catalyst consisting of a soluble vanadium compoundand an alkylaluminum halide compound or a zirconium catalyst consistingof a metallocene compound of zirconium and an organoaluminum oxycompound.

[0276] Examples of suitable soluble vanadium compounds for use in thevanadium catalyst include vanadium tetrachloride, vanadiumoxytrichloride, monoethoxyvanadium dichloride, vanadiumtriacetylacetonate and oxyvanadium triacetylacetonate.

[0277] Examples of suitable alkylaluminum halide compounds for use inthe vanadium catalyst include ethylaluminum dichloride, diethylaluminummonochloride, ethylaluminum sesquichloride, diethylaluminum monobromide,diisobutylaluminum monochloride, isobutylaluminum dichloride andisobutylaluminum sesquichloride.

[0278] Examples of suitable zirconium metallocene compounds for use inthe zirconium catalyst include:

[0279] ethylenebis(indenyl)zirconium dibromide,

[0280] dimethylsilylenebis(2-methylindenyl)zirconium dichloride,

[0281] bis(cyclopentadienyl)zirconium dibromide, and

[0282] bis(dimethylcyclopentadienyl)zirconium dichloride.

[0283] Examples of suitable organoaluminum oxy compounds for use in thezirconium catalyst include aluminooxane and benzene-insolubleorganoaluminum oxy compounds.

[0284] The zirconium catalyst may contain an organoaluminum compoundtogether with the metallocene compound of zirconium and theorganoaluminum oxy compound.

[0285] Examples of suitable organoaluminum compounds includetriisobutylaluminum, dimethylaluminum chloride and methylaluminumsesquichloride.

[0286] This polymerization can be performed in a solution, a suspensionor an intermediate form. In any case, it is preferred that an inertsolvent be used as a reaction medium.

[0287] The modified polyolefin (B) for use in this invention can beobtained by grafting the above unmodified ethylene/α-olefin randomcopolymer with a given amount of an unsaturated carboxylic acid or aderivative thereof.

[0288] In the modified polyolefin (B) for use in this invention, theamount of graft of unsaturated carboxylic acid or derivative thereof isin the range of 0.1 to 4.0% by weight, preferably 0.5 to 2.5% by weight,per 100% by weight of unmodified ethylene/α-olefin random copolymer.

[0289] The modified polyolefin (B) whose graft amount is in the aboverange is excellent in the dispersibility in the elastomer compositionfor crosslinked olefin elastomer foam, has excellent thermal stabilityand is free from coloring of molten resin. Further, the use of thismodified polyolefin (B) enables preparation of an elastomer compositionfrom which a crosslinked foam excellent in mechanical strength can beproduced.

[0290] Examples of suitable unsaturated carboxylic acids for use in theabove modification include acrylic acid, maleic acid, fumaric acid,tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid,isocrotonic acid and Nadic acid (trade name,endocis-bicyclo(2,2,1)hept-5-ene-2,3-dicarboxylic acid).

[0291] Examples of suitable derivatives of unsaturated carboxylic acidsinclude acid halide compounds, amide compounds, imide compounds, acidanhydrides and ester compounds derived from the above unsaturatedcarboxylic acids. Specific examples thereof include maleyl chloride,maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate,dimethyl maleate and glycidyl maleate. Of these, unsaturateddicarboxylic acids and anhydrides thereof are preferred. Maleic acid,Nadic acid (trade name) and anhydrides thereof are especially preferred.

[0292] The above modified polyolefin (B) can be produced by variouscustomary processes such as:

[0293] (1) process in which an unsaturated carboxylic acid or aderivative thereof is added to the above unmodified ethylene/α-olefinrandom copolymer in molten form and a graft copolymerization is carriedout; and

[0294] (2) process in which the above unmodified ethylene/α-olefinrandom copolymer is dissolved in a solvent, an unsaturated carboxylicacid or a derivative thereof is added to the solution and a graftcopolymerization is carried out.

[0295] In all these processes, it is preferred from the viewpoint ofefficient graft copolymerization of a graft monomer such as the aboveunsaturated carboxylic acid that the grafting reaction be performed inthe presence of a radical initiator.

[0296] An organic peroxide, an azo compound or the like can be used asthe radical initiator. Examples of suitable radical initiators include:

[0297] organic peroxides such as benzoyl peroxide, dichlorobenzoylperoxide, dicumyl peroxide, di-tert-butyl peroxide,2,5-dimethyl-2,5-di(peroxidobenzoato)hexyne-3,1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butylperacetate, 2,5-dimethyl-2,5-di(tert-butylperoxido)hexyne-3,2,5-dimethyl-2,5-di(tert-butylperoxido)hexane, tert-butyl perbenzoate,tert-butyl perphenylacetate, tert-butyl perisobutylate, tert-butylper-sec-octoate, tert-butyl perpivalate, cumyl perpivalate andtert-butyl perdiethylacetate; and

[0298] azo compounds such as azobisisobutyronitrile and dimethylazoisobutylate. Of these, dialkyl peroxides such as dicumyl peroxide,di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3,2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and1,4-bis(tert-butylperoxyisopropyl)benzene are preferably used.

[0299] The above radical initiator is generally used in an amount of0.01 to 0.10 parts by weight, preferably 0.02 to 0.08 parts by weight,and still preferably 0.02 to 0.05 parts by weight, per 100 parts byweight of unmodified ethylene/α-olefin random copolymer.

[0300] In both the graft reaction in which the above radical initiatoris used and the graft reaction in which no radical initiator is used,the reaction temperature is generally set at 60 to 350° C., preferably150 to 300° C.

[0301] In the second elastomer composition for crosslinked olefinelastomer foam according to the present invention, the modifiedpolyolefin (B) is used in an amount of 5 to 30 parts by weight,preferably 5 to 20 parts by weight, and still preferably 5 to 15 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A) (or mixture of ethylene/α-olefin copolymer (A1) andethylene/α-olefin copolymer (A2)) and modified polyolefin (B). The useof the modified polyolefin (B) in the above amounts enables preparationof an elastomer composition from which a crosslinked foam having a lowspecific gravity and being excellent in compression set, mechanicalstrength (particularly tear strength) and adhesive strength can beproduced.

[0302] In the fifth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the modifiedpolyolefin (B) is used in an amount of 5 to 30 parts by weight,preferably 5 to 20 parts by weight, and still preferably 5 to 15 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A), modified polyolefin (B) and high-pressure processedlow-density polyethylene (C). The use of the modified polyolefin (B) inthe above amounts enables preparation of an elastomer composition fromwhich a crosslinked foam having a high specific gravity and beingexcellent in compression set, tear strength and adhesion and high inhardness can be produced.

[0303] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the modifiedpolyolefin (B) is used in an amount of 5 to 30 parts by weight,preferably 5 to 20 parts by weight, and still preferably 5 to 15 partsby weight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (A1), ethylene/α-olefin copolymer (A2), modified polyolefin(B) and high-pressure processed low-density polyethylene (C). The use ofthe modified polyolefin (B) in the above amounts enables preparation ofan elastomer composition from which a crosslinked foam having a highspecific gravity and being excellent in compression set, tear strengthand adhesion and high in hardness can be produced.

[0304] (High-Pressure Processed Low-Density Polyethylene (C))

[0305] The high-pressure processed low-density polyethylene (C) for usein the present invention is an ethylene homopolymer or a copolymer ofethylene and an α-olefin having 3 to 20 carbon atoms. The densitythereof is in the range of 0.91 to less than 0.93 g/cm³, preferably 0.91to 0.92 g/cm³.

[0306] Examples of suitable α-olefins include propylene, 1-butene,1-pentene, 2-methyl-1-butene, 3-methyl-1-butene, 1-hexene,3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene,1-heptene, methyl-1-hexene, dimethyl-1-pentene, trimethyl-1-butene,ethyl-1-pentene, 1-octene, methyl-1-pentene, dimethyl-1-hexene,trimethyl-1-pentene, ethyl-1-hexene, methylethyl-1-pentene,diethyl-1-butene, propyl-1-pentene, 1-decene, methyl-1-nonene,dimethyl-1-octene, trimethyl-1-heptene, ethyl-1-octene,methylethyl-1-heptene, diethyl-1-hexene, 1-dodecene and 1-hexadecene.These α-olefins can be used either individually or in combination.

[0307] The melt flow rate (MFR measured at 190° C. under a load of 2.16kg in accordance with ASTM D 1238) of the high-pressure processedlow-density polyethylene (C) for use in the present invention is in therange of 0.1 to 50 g/10 min, preferably 0.5 to 50 g/10 min, and stillpreferably 0.5 to 20 g/10 min.

[0308] In the third elastomer composition for crosslinked olefinelastomer foam according to the present invention, the high-pressureprocessed low-density polyethylene (C) is used in an amount of 5 to 50parts by weight, preferably 10 to 40 parts by weight, and stillpreferably 15 to 30 parts by weight, per 100 parts by weight of thetotal of ethylene/α-olefin. copolymer (A) and high-pressure processedlow-density polyethylene (C). The use of the high-pressure processedlow-density polyethylene (C) in the above amounts enables preparation ofan elastomer composition from which a crosslinked foam having a highhardness and excellent tear strength can be produced.

[0309] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the high-pressureprocessed low-density polyethylene (C) is used in an amount of 5 to 50parts by weight, preferably 10 to 40 parts by weight, and stillpreferably 15 to 30 parts by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2) and high-pressure processed low-density polyethylene (C). The useof the high-pressure processed low-density polyethylene (C) in the aboveamounts enables preparation of an elastomer composition from which acrosslinked foam having a high hardness and excellent tear strength canbe produced.

[0310] In the fifth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the high-pressureprocessed low-density polyethylene (C) is used in an amount of 5 to 50parts by weight, preferably 10 to 40 parts by weight, and stillpreferably 15 to 30 parts by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A), modified polyolefin (B) andhigh-pressure processed low-density polyethylene (C). The use of thehigh-pressure processed low-density polyethylene (C) in the aboveamounts enables preparation of an elastomer composition from which acrosslinked foam having a high hardness and excellent tear strength canbe produced.

[0311] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the high-pressureprocessed low-density polyethylene (C) is used in an amount of 5 to 50parts by weight, preferably 10 to 40 parts by weight, and stillpreferably 15 to 30 parts by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C). The use of the high-pressure processed low-densitypolyethylene (C) in the above amounts enables preparation of anelastomer composition from which a crosslinked foam having a highhardness and excellent tear strength can be produced.

[0312] (Organic Peroxide (D))

[0313] The organic peroxide (D) for use as a crosslinking agent in thisinvention is the same as employed in the preparation of the above firstcrosslinked olefin elastomer foam and elastomer composition thereforaccording to the present invention.

[0314] In the second elastomer composition for crosslinked olefinelastomer foam according to the present invention, the organic peroxide(D) is generally used in an amount of 0.1 to 1.5 parts by weight,preferably 0.2 to 1.0 part by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A) (or mixture ofethylene/α-olefin copolymer (A1) and ethylene/α-olefin copolymer (A2))and modified polyolefin (B).

[0315] In the third elastomer composition for crosslinked olefinelastomer foam according to the present invention, the organic peroxide(D) is generally used in an amount of 0.1 to 1.5 parts by weight,preferably 0.2 to 1.0 part by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A) and high-pressure processedlow-density polyethylene (C).

[0316] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the organic peroxide(D) is generally used in an amount of 0.1 to 1.5 parts by weight,preferably 0.2 to 1.0 part by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2) and high-pressure processed low-density polyethylene (C).

[0317] In the fifth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the organic peroxide(D) is generally used in an amount of 0.1 to 1.5 parts by weight,preferably 0.2 to 1.0 part by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A), modified polyolefin (B) andhigh-pressure processed low-density polyethylene (C).

[0318] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the organic peroxide(D) is generally used in an amount of 0.1 to 1.5 parts by weight,preferably 0.2 to 1.0 part by weight, per 100 parts by weight of thetotal of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C).

[0319] The use of the organic peroxide (D) together with thecrosslinking auxiliary (E) in the above amounts enables obtaining acrosslinked foam with appropriate crosslink structure.

[0320] (Crosslinking Auxiliary (E))

[0321] The crosslinking auxiliary (E) for use in this invention is thesame as employed in the preparation of the above first crosslinkedolefin elastomer foam and elastomer composition therefor according tothe present invention.

[0322] In the present invention, the crosslinking auxiliary (E) ispreferably used at a weight ratio of crosslinking auxiliary (E) toorganic peroxide (D) ((E)/(D)) of 1/10 to 5/1, still preferably 1/8 to3/1, and optimally 1/5 to 2/1.

[0323] (Foaming Agent (F))

[0324] The foaming agent (F) for use in this invention is the same asemployed in the preparation of the above first crosslinked olefinelastomer foam and elastomer composition therefor according to thepresent invention.

[0325] In the second elastomer composition for crosslinked olefinelastomer foam according to the present invention, the foaming agent (F)is generally used in an amount of 3 to 20 parts by weight, preferably 5to 15 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A) (or mixture of ethylene/α-olefincopolymer (A1) and ethylene/α-olefin copolymer (A2)) and modifiedpolyolefin (B).

[0326] In the third elastomer composition for crosslinked olefinelastomer foam according to the present invention, the foaming agent (F)is generally used in an amount of 3 to 20 parts by weight, preferably 5to 15 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A) and high-pressure processed low-densitypolyethylene (C).

[0327] In the fourth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the foaming agent (F)is generally used in an amount of 3 to 20 parts by weight, preferably 5to 15 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer (A2) andhigh-pressure processed low-density polyethylene (C).

[0328] In the fifth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the foaming agent (F)is generally used in an amount of 3 to 20 parts by weight, preferably 5to 15 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A), modified polyolefin (B) andhigh-pressure processed low-density polyethylene (C).

[0329] In the sixth elastomer composition for crosslinked olefinelastomer foam according to the present invention, the foaming agent (F)is generally used in an amount of 3 to 20 parts by weight, preferably 5to 15 parts by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer (A2),modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C).

[0330] The use of the foaming agent (F) in the above amounts enablesobtaining a foam molding with high expansion ratio and high closed cellratio. The amount of added foaming agent (F) is decided taking intoaccount the expansion ratio of crosslinked foam.

[0331] Production of Second to Sixth Elastomer Compositions

[0332] Each of the above second, third, fourth, fifth and sixthelastomer compositions for crosslinked olefin elastomer foam accordingto the present invention is a noncrosslinked nonfoamed composition,which may be in molten form or in the form of pellets or a sheetobtained by cooling the melt to effect solidification.

[0333] Pellets of the second elastomer composition for crosslinkedolefin elastomer foam according to the present invention can be producedby, for example, mixing together the above ethylene/α-olefin copolymer(A) (or mixture of ethylene/α-olefin copolymer (A1) andethylene/α-olefin copolymer (A2)), modified polyolefin (B), organicperoxide (D), crosslinking auxiliary (E) and foaming agent (F) in theabove amounts by means of Henschel mixer or the like, and melting andplasticizing the mixture by means of a blender such as a banbury mixer,an extruder or the like at such a temperature that the foaming agent (F)and organic peroxide (D) are not decomposed to thereby effecthomogeneous mixing and dispersion, followed by pelletization by means ofa pelletizer.

[0334] Pellets of the third, fourth, fifth and sixth elastomercompositions for crosslinked olefin elastomer foam according to thepresent invention can be produced in the same manner as described abovewith respect to the production of pellets of the second elastomercomposition for crosslinked olefin elastomer foam according to thepresent invention.

[0335] These compositions can optionally be loaded with variousadditives such as such as a filler, a heat stabilizer, a weatheringstabilizer, a flame retarder, a hydrochloric acid absorber and a pigmentin addition to the above components to an extent such that the object ofthe present invention is not departed from.

[0336] On the other hand, sheets of the second, third, fourth, fifth andsixth elastomer compositions for crosslinked olefin elastomer foamaccording to the present invention can be produced by, for example,sheeting the above obtained pellets of the compositions by the use of anextruder or a calendering machine. Alternatively, the foamable sheet inthe noncrosslinked and nonfoamed state can be produced by blendingtogether composition components by means of, for example, BrabenderPlastograph and, thereafter, sheeting the blend by means of calenderrolls or a press molding machine. Furthermore, the foamable sheet can beproduced by blending composition components by means of an extruder and,thereafter, sheeting the blend through T dies or annular dies.

[0337] Production of Second to Sixth Crosslinked Olefin Elastomer Foams

[0338] The second, third, fourth, fifth and sixth crosslinked olefinelastomer foams of the present invention can be produced from the abovesecond, third, fourth, fifth and sixth elastomer compositions forcrosslinked olefin elastomer foam according to the present invention,respectively, in the same manner as described above with respect to theproduction of the first crosslinked olefin elastomer foam of the presentinvention.

[0339] It is preferred that each of the second to sixth crosslinkedolefin elastomer foams of the present invention which are produced inthe above manner have a specific gravity (JIS K 7112) of 0.05 to 0.2, anexpansion ratio of 8 to 15, a compression set (JIS K 6301) of 30 to 60%and a tear strength (BS5131-2.6) of 1.5 to 2.5 kg/cm.

[0340] Secondarily compressed crosslinked foams can be obtained from theabove crosslinked foams by the aforementioned method. Each of thesecondarily compressed crosslinked foams preferably has a specificgravity of 0.1 to 0.2, a compression set of 20 to 60% and a tearstrength of 2.0 to 4.0 kg/cm.

[0341] The seventh crosslinked olefin elastomer foam and elastomercomposition therefor according to the present invention will bedescribed in detail below.

[0342] Seventh Crosslinked Foam

[0343] The seventh crosslinked foam of the present invention is acrosslinked foam obtained by heating an olefin elastomer compositioncomprising an ethylene/α-olefin copolymer (G), a polypropylene (H), anorganic peroxide (D), a crosslinking auxiliary (E) and a foaming agent(F).

[0344] The seventh elastomer composition for crosslinked olefinelastomer foam according to the present invention is a noncrosslinkednonfoamed composition which is crosslinked and foamed when heated atgiven temperature or higher, and comprises a specified ethylene/α-olefincopolymer (G), a polypropylene (H), an organic peroxide (D), acrosslinking auxiliary (E) and a foaming agent (F).

[0345] Ethylene/α-olefin Copolymer (G)

[0346] The ethylene/α-olefin copolymer (G) for use in the presentinvention is an amorphous or lowly crystalline random copolymer preparedfrom ethylene and an α-olefin having 3 to 20 carbon atoms. It ispreferably a soft ethylene/α-olefin copolymer having a density (ASTM D1505) of 0.88 to 0.92 g/cm³ and a melt flow rate (MFR measured at 190°C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50g/10 min, especially 0.5 to 20 g/10 min.

[0347] The α-olefin copolymerized with ethylene is an α-olefin having 3to 20 carbon atoms, which can be selected from among, for example,propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene,1-decene, 1-undecene, 1-dodecene, 1-hexadecene, 1-octadecene,1-nonadecene, 1-eicosene and 4-methyl-1-pentene. Of these, α-olefinshaving 3 to 10 carbon atoms are preferred. Propylene, 1-butene, 1-hexeneand 1-octene are especially preferred. These α-olefins can be usedeither individually or in combination.

[0348] It is preferred that the ethylene/α-olefin copolymer (G) containunits derived from ethylene in an amount of 85 to 93 mol % and unitsderived from α-olefins having 3 to 20 carbon atoms in an amount of 7 to15 mol %.

[0349] The composition of the ethylene/α-olefin copolymer (G) isgenerally determined by homogeneously dissolving about 200 mg of thecopolymer in 1 ml of hexachlorobutadiene in a sample tube of 10 mmdiameter to thereby obtain a sample solution and subjecting the samplesolution to ¹³C-NMR spectroscopy under the conditions such that themeasuring temperature is 120° C., the measuring frequency 25.05 MHz, thespectrum width 1500 Hz, the pulse cycle time 4.2 sec and the pulse width6 μsec.

[0350] Furthermore, the ethylene/α-olefin copolymer (G) may containunits derived from other polymerizable monomers than the above monomersto an extent such that the object of the present invention is notdeparted from.

[0351] Examples of suitable ethylene/α-olefin copolymers (G) includeethylene/propylene random copolymer, ethylene/1-butene random copolymer,ethylene/propylene/1-butene random copolymer,ethylene/propylene/ethylidenenorbornene random copolymer,ethylene/1-hexene random copolymer and ethylene/1-octene randomcopolymer. Of these, ethylene/propylene random copolymer,ethylene/1-butene random copolymer, ethylene/1-hexene random copolymerand ethylene/1-octene random copolymer are preferred. These copolymersmay be used in combination.

[0352] The ethylene/α-olefin copolymer (G) for use in this inventiongenerally has a crystallinity, as measured by X-ray diffractometry, of40% or below, preferably 10 to 30%.

[0353] This ethylene/α-olefin copolymer (G) can be produced by theconventional process in which use is made of a vanadium catalyst, atitanium catalyst, a metallocene catalyst or the like.

[0354] The ethylene/α-olefin copolymer (G) is used in an amount of 70 to98 parts by weight, preferably 80 to 95 parts by weight, per 100 partsby weight of the total of ethylene/α-olefin copolymer (G) andpolypropylene (H). The use of the ethylene/α-olefin copolymer (G) in theabove amounts enables preparation of a composition from which acrosslinked foam having a low specific gravity and being excellent inthe balance of flexibility, surface hardness, abrasion resistance, tearstrength property and heat resistance can be produced.

[0355] Polypropylene (H)

[0356] The polypropylene (H) for use in the present invention can be anyof propylene homopolymer, propylene block copolymers andpropylene/α-olefin random copolymers. These can be used eitherindividually or in combination.

[0357] The melt flow rate (MFR measured at 230° C. under a load of 2.16kg in accordance with ASTM D 1238) of the propylene homopolymer for usein the present invention is generally in the range of 0.5 to 50 g/10min, preferably 1 to 20 g/10 min.

[0358] The propylene block copolymer for use in the present invention isgenerally one prepared from propylene and ethylene or an α-olefin having4 to 10 carbon atoms, and the melt flow rate (MFR measured at 230° C.under a load of 2.16 kg in accordance with ASTM D 1238) thereof isgenerally in the range of 0.5 to 50 g/10 min, preferably 1 to 20 g/10min.

[0359] The α-olefin having 4 to 10 carbon atoms for blockcopolymerization with propylene can be, for example, any of 1-butene,1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene and4-methyl-1-pentene. Of these, ethylene, 1-butene, 1-hexene and 1-octeneare preferred. The α-olefins can be used either individually or incombination.

[0360] It is preferred that the propylene block copolymer contain unitsderived from propylene in an amount of 80 to 95 mol % and units derivedfrom ethylene or an α-olefin having 4 to 10 carbon atoms in an amount of5 to 20 mol %.

[0361] The propylene block copolymer is preferably a propylene/ethyleneblock copolymer.

[0362] The propylene/α-olefin random copolymer for use in the presentinvention is an amorphous or lowly crystalline random copolymer preparedfrom propylene and ethylene and/or an α-olefin having 4 to 20 carbonatoms. It is preferably a soft propylene/α-olefin random copolymerhaving a melt flow rate (MFR measured at 230° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.5 to 50 g/10 min, especially 1 to20 g/10 min.

[0363] As the α-olefin having 4 to 20 carbon atoms copolymerized withpropylene, there can be mentioned, for example, α-olefins having 4 to 20carbon atoms such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-hexadecene, 1-octadecene,1-nonadecene, 1-eicosene and 4-methyl-1-pentene. Of the α-olefinscopolymerized with propylene, ethylene and α-olefins having 4 to 10carbon atoms are preferred. Ethylene, 1-butene, 1-hexene and 1-octeneare especially preferred. These α-olefins can be used eitherindividually or in combination.

[0364] It is preferred that the propylene/α-olefin random copolymercontain units derived from propylene in an amount of 70 to 98 mol % andunits derived from ethylene and α-olefins having 4 to 20 carbon atoms inan amount of 2 to 30 mol %.

[0365] Examples of suitable propylene/α-olefin random copolymers includepropylene/ethylene random copolymer, propylene/1-butene randomcopolymer, propylene/ethylene/1-butene random copolymer,propylene/ethylene/ethylidenenorbornene random copolymer,propylene/1-hexene random copolymer and propylene/1-octene randomcopolymer. Of these, propylene/ethylene random copolymer,propylene/1-butene random copolymer, propylene/1-hexene random copolymerand propylene/1-octene random copolymer are preferred. These copolymersmay be used in combination.

[0366] These propylene/α-olefin random copolymers generally have amelting point, as measured by the DSC method, of 150° C. or below,preferably 125 to 145° C.

[0367] In the present invention, use is made of polypropylene (H) havingsuch a melt flow rate that the melt flow rate (MFR measured at 230° C.under a load of 2.16 kg in accordance with ASTM D 1238) of the mixtureof ethylene/α-olefin copolymer (G) and polypropylene (H) is in the rangeof 0.1 to 10 g/10 min, preferably 0.5 to 10 g/10 min.

[0368] The polypropylene (H) is used in an amount of 2 to 30 parts byweight, preferably 5 to 20 parts by weight, per 100 parts by weight ofthe total of ethylene/α-olefin copolymer (G) and polypropylene (H). Theuse of the polypropylene (H) in the above amounts enables preparation ofa composition from which a foam having a low specific gravity and beingexcellent in the balance of flexibility, surface hardness, abrasionresistance, tear strength property and heat resistance can be produced.

[0369] Organic Peroxide (D)

[0370] The organic peroxide (D) for use as a crosslinking agent in thisinvention is the same as employed in the preparation of the above firstcrosslinked olefin elastomer foam and elastomer composition thereforaccording to the present invention.

[0371] In the present invention, the organic peroxide (D) is generallyused in an amount of 0.1 to 1.5 parts by weight, preferably 0.2 to 1.0part by weight, per 100 parts by weight of the total ofethylene/α-olefin copolymer (G) and polypropylene (H). The use of theorganic peroxide (D) together with the crosslinking auxiliary (E) in theabove amounts enables obtaining a crosslinked foam with appropriatecrosslink structure.

[0372] Crosslinking Auxiliary (E)

[0373] The crosslinking auxiliary (E) for use in this invention is thesame as employed in the preparation of the above first crosslinkedolefin elastomer foam and elastomer composition therefor according tothe present invention.

[0374] In the present invention, the crosslinking auxiliary (E) ispreferably used at a weight ratio of crosslinking auxiliary (E) toorganic peroxide (D) ((E)/(D)) of 1/10 to 5/1, still preferably 1/8 to3/1, and optimally 1/5 to 2/1.

[0375] Foaming Agent (F)

[0376] The foaming agent (F) for use in this invention is the same asemployed in the preparation of the above first crosslinked olefinelastomer foam and elastomer composition therefor according to thepresent invention.

[0377] In the present invention, the foaming agent (F) is generally usedin an amount of 3 to 20 parts by weight, preferably 5 to 15 parts byweight, per 100 parts by weight of the total of ethylene/α-olefincopolymer (G) and polypropylene (H). The use of the foaming agent (F) inthe above amounts enables obtaining a foam molding with high expansionratio and high closed cell ratio. The amount of added foaming agent (F)is decided taking into account the expansion ratio of crosslinked foam.

[0378] Production of Seventh Elastomer Composition

[0379] The seventh elastomer composition for crosslinked olefinelastomer foam according to the present invention is a noncrosslinkednonfoamed composition, which may be in molten form or in the form ofpellets or a sheet obtained by cooling the melt to effectsolidification.

[0380] Pellets of the seventh elastomer composition for crosslinkedolefin elastomer foam according to the present invention can be producedby, for example, mixing together the above ethylene/α-olefin copolymer(G), polypropylene (H), organic peroxide (D), crosslinking auxiliary (E)and foaming agent (F) in the above amounts by means of Henschel mixer orthe like, and melting and plasticizing the mixture by means of a blendersuch as a banbury mixer, an extruder or the like at such a temperaturethat the foaming agent (F) and organic peroxide (D) are not decomposedto thereby effect homogeneous mixing and dispersion, followed bypelletization by means of a pelletizer.

[0381] This composition can optionally be loaded with various additivessuch as such as a filler, a heat stabilizer, a weathering stabilizer, aflame retarder, a hydrochloric acid absorber and a pigment in additionto the above components to an extent such that the object of the presentinvention is not departed from.

[0382] On the other hand, a sheet of the seventh elastomer compositionfor crosslinked olefin elastomer foam according to the present inventioncan be produced by, for example, sheeting the above obtained pellets ofthe composition by the use of an extruder or a calendering machine.Alternatively, the foamable sheet in the noncrosslinked and nonfoamedstate can be produced by blending together composition components bymeans of, for example, Brabender Plastograph and, thereafter, sheetingthe blend by means of calender rolls or a press molding machine.Furthermore, the foamable sheet can be produced by blending compositioncomponents by means of an extruder and, thereafter, sheeting the blendthrough T dies or annular dies.

[0383] Production of Seventh Crosslinked Olefin Elastomer Foam

[0384] The seventh crosslinked olefin elastomer foam of the presentinvention can be produced from the above seventh elastomer compositionfor crosslinked olefin elastomer foam according to the presentinvention, for example, in the same manner as described above withrespect to the production of the first crosslinked olefin elastomer foamof the present invention.

[0385] It is preferred that the seventh crosslinked olefin elastomerfoam of the present invention which is produced in the above manner havea specific gravity (JIS K 7112) of 0.05 to 0.2, an expansion ratio of 8to 15, a compression set (JIS K 6301) of 30 to 60% and a tear strength(BS5131-2.6) of 1.5 to 2.5 kg/cm.

[0386] Secondarily compressed crosslinked foam can be obtained from theabove crosslinked foam by the aforementioned method. The secondarilycompressed crosslinked foam preferably has a specific gravity of 0.1 to0.2, a compression set of 20 to 60% and a tear strength of 2.0 to 4.0kg/cm.

EFFECT OF THE INVENTION

[0387] The crosslinked olefin elastomer foam of the present inventionhas a high expansion ratio, is free from surface roughening attributedto defoaming, realizes a soft touch, exhibits a low compression set andis excellent in tear strength property and heat resistance.

[0388] Also, the secondarily compressed crosslinked foam, that is, othercrosslinked olefin elastomer foam of the present invention is free fromsurface roughening attributed to defoaming, realizes a soft touch,exhibits a low compression set and is excellent in tear strengthproperty and heat resistance.

[0389] The elastomer composition for crosslinked olefin elastomer foamaccording to the present invention enables producing the crosslinkedolefin elastomer foam (including the secondarily compressed crosslinkedfoam) of the present invention which can exert these effects.

[0390] The crosslinked olefin elastomer foam (including the secondarilycompressed crosslinked foam) of the present invention is suitable toapplication in automobile parts such as weatherstrips and side shields,foot gears such as shoe soles and sandals, cable coverings, sportsgoods, grips, gaskets, construction materials, leisure goods, etc.

EXAMPLE

[0391] The present invention will further be illustrated below withreference to the following Examples which in no way limit the scope ofthe invention.

[0392] With respect to the foams obtained in the Examples andComparative Examples, the expansion ratio, compression set and tearstrength were measured by the following methods, and the soft touch andfoaming uniformity were evaluated by the following methods.

[0393] (1) Expansion ratio:

[0394] The expansion ratio is the quotient obtained by dividing thedensity of nonfoamed item assumed to be 980 kg/m³ by the apparentdensity of foam.

[0395] (2) Compression set:

[0396] The compression set was determined by carrying out a compressionset test in accordance with Japanese Industrial Standard (JIS) K 6301under conditions such that a compression of 50% compression ratio wasapplied at 50° C. for 6 hr.

[0397] (3) Tear strength:

[0398] The tear strength was determined by carrying out a tear strengthtest at a pulling speed of 10 mm/min in accordance with BS5131-2.6.

[0399] (4) Soft touch:

[0400] Hand was put on a foam surface, and the soft touch of the foamwas rated on the basis of the sensation into the following 5 grades.

[0401] Five-Grade Rating

[0402] 5: surface is even, giving soft sensation;

[0403] 4: surface is slightly sandy, still giving soft sensation;

[0404] 3: intermediate between grades 2 and 4;

[0405] 2: surface is sandy, giving slightly hard sensation; and

[0406] 1: surface is rough, giving resin-like hard sensation.

[0407] (5) Foaming uniformity:

[0408] The state of a foam section was visually inspected, and thefoaming uniformity was rated on the basis of the state into thefollowing four grades.

[0409] Four-Grade Rating

[0410] AA: both cell size and morphology are highly uniform,

[0411] A: both cell size and morphology are uniform,

[0412] B: both cell size and morphology are slightly nonuniform, and

[0413] C: both cell size and morphology are extremely irregular.

Production Example 1

[0414] (Production of long-chain branched ethylene/1-butene copolymer(A-3))

[0415] (Preparation of catalyst solution)

[0416] 0.63 mg ofrac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconiumdichloride was placed in a glass flask satisfactorily purged withnitrogen. Further, 1.57 ml of a toluene solution of methylaluminooxane(A1: 0.13 mmol/lit.) and 2.43 ml of toluene were added thereto, therebyobtaining a catalyst solution.

[0417] (Polymerization)

[0418] 912 ml of hexane and 86 ml of 1-butene were charged into astainless steel autoclave of 2 lit. internal volume satisfactorilypurged with nitrogen, and the internal temperature was raised to 60° C.Subsequently, 0.9 mmol of triisobutylaluminum and 2.0 ml of the abovecatalyst solution (0.0005 mmol in terms of Zr) were introduced underpressure with ethylene to thereby initiate polymerization. Thereafter,ethylene only was continuously fed to thereby maintain the totalpressure at 24.0 kg/cm²-G. Polymerization was conducted at 150° C. for30 min.

[0419] A small amount of ethanol was introduced into the reaction systemto thereby terminate the polymerization, and unreacted ethylene wasdischarged. The thus obtained polymer was placed in a large excess ofmethanol so that the polymer was precipitated. The polymer was recoveredby filtration and dried in vacuum overnight. Thus, a long-chain branchedethylene/1-butene copolymer (A-3) was obtained.

[0420] The obtained copolymer had an ethylene content of 89 mol %; a1-butene content of 11 mol %; a density of 0.89 g/cm³; a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 3.6 g/10 min; a crystallinity, as measured by X-raydiffractometry, of 18%; a molecular weight distribution (Mw/Mn), asdetermined by GPC, of 1.9; a gη* value of 0.89; and a melt tension, asmeasured by the following method, of 1.2 g.

[0421] Method of measuring melt tension:

[0422] Pellets of the ethylene/1-butene copolymer were melted at 190°C., and a strand was extruded through nozzle (L=8 mm and D=2.095 mm) anddrawn, The melt tension at the time of strand drawing was measured.

Production Example 2

[0423] (Production of linear ethylene/1-butene copolymer (A-1))

[0424] A catalyst solution was prepared in the same manner as inProduction Example 1 except thatbis(1,3-dimethylcyclopentadienyl)zirconium dichloride was used in placeof rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconiumdichloride.

[0425] A linear ethylene/1-butene copolymer (A-1) was produced in thesame manner as in Production Example 1 except that the above catalystsolution was used, 175 ml of 1-butene was added and copolymerizationreaction of ethylene and 1-butene was performed at 90° C. and at a totalpressure of 8.0 kg/cm²-G while feeding hydrogen at a rate of 80 ml/hr.

[0426] The obtained copolymer had an ethylene content of 91 mol %; a1-butene content of 9 mol %; a density of 0.89 g/cm³; a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 3.6 g/10 min; a crystallinity, as measured by X-raydiffractometry, of 20%; a molecular weight distribution (Mw/Mn), asdetermined by GPC, of 2.1; a gη* value of 1.00; and a melt tension of0.5 g.

Example A1

[0427] A mixture consisting of:

[0428] 100 parts by weight of linear ethylene/1-butene copolymer (A-1)having an ethylene content of 91 mol %, a density (ASTM D 1505) of 0.89g/cm³, an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 3.6 g/10 min, an Mw/Mn of 2.1 and a gη* value of1.00, obtained in Product-ion Example 2;

[0429] 0.5 part by weight of dicumyl peroxide (DCP);

[0430] 0.35 part by weight (in terms of TAIC contents) of triallylisocyanurate (TAIC) (trade name: M-60 (TAIC content 60%), produced byNippon Kasei Chemical Co., Ltd.);

[0431] 7 parts by weight of azodicarbonamide; and

[0432] 10 parts by weight of talc, was milled by means of rolls whosesurface temperature was set at 100° C. for 10 min, and sheeted.

[0433] The obtained sheet was charged into a press metal mold and heatedunder a pressure of 150 kg/cm² at 160° C. for 12 min. Thus, a foam (24.5mm thickness, 150 mm length and 200 mm width) was obtained.

[0434] The expansion ratio, compression set and tear strength of theobtained foam were measured by the above methods, and the soft touch andfoaming uniformity were evaluated by the above methods. The results aregiven in Table 1.

Example A2

[0435] The same procedure as in Example A1 was repeated except that 50parts by weight of the linear ethylene/1-butene copolymer (A-1) employedin Example A1 and 50 parts by weight of linear ethylene/1-hexenecopolymer (A-2) having an ethylene content of 95 mol %, a density (ASTMD 1505) of 0.91 g/cm³, an MFR (measured at 190° C. under a load of 2.16kg in accordance with ASTM D 1238) of 4.0 g/10 min, an Mw/Mn of 2.0 anda gη* value of 1.00 were used in place of the 100 parts by weight oflinear ethylene/1-butene copolymer (A-1). The results are given in Table1.

Example A3

[0436] The same procedure as in Example A1 was repeated except that theamounts of added dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC)were changed to 0.8 part by weight and 0.1 part by weight (in terms ofTAIC contents), respectively. The results are given in Table 1.

Example A4

[0437] The same procedure as in Example A1 was repeated except that theamounts of added dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC)were changed to 0.2 part by weight and 0.6 part by weight (in terms ofTAIC contents), respectively. The results are given in Table 1.

Example A5

[0438] The same procedure as in Example A1 was repeated except that 10parts by weight of sodium hydrogencarbonate was used in place of theazodicarbonamide. The results are given in Table 1.

Example A6

[0439] The same procedure as in Example A1 was repeated except that thelong-chain branched ethylene/1-butene copolymer (A-3) having an ethylenecontent of 89 mol %, a density (ASTM D 1505) of 0.89 g/cm³, an MFR(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 3.6 g/10 min, an Mw/Mn of 1.9 and a gη* value of 0.89, producedin Production Example 1, was used in place of the linearethylene/1-butene copolymer (A-1). The results are given in Table 1.

Comparative Example A1

[0440] The same procedure as in Example A1 was repeated except that thetriallyl isocyanurate (TAIC) was not used. The results are given inTable 1.

Comparative Example A2

[0441] The same procedure as in Example A1 was repeated except that anethylene/vinyl acetate copolymer having a vinyl acetate content of 19%by weight, a density (ASTM D 1505) of 0.94 g/cm³ and an MFR (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 2.5g/10 min was used in place of the linear ethylene/1-butene copolymer(A-1). The results are given in Table 1. TABLE 1 Example Comp. Ex. A1 A2A3 A4 A5 A6 A1 A2 Formulation of olefin elastomer compsn. (pts. wt.)ethylene/ α-olefin copolymer linear ethylene/1-butene copolymer (A-1)100 50 100 100 100 — 100 — linear ethylene/1-hexene copolymer (A-2) — 50— — — — — — long-chain branched ethylene/1-butene — — — — — 100 — —copolymer (A-3) ethylene/vinyl acetate copolymer — — — — — — — 100crosslinking agent DCP 0.5 0.5 0.8 0.2 0.5 0.5 0.5 0.5 crosslinkingauxiliary TAIC 0.35 0.35 0.1 0.6 0.35 0.35 0 0.36 foaming agentazodicarbonamide 7 7 7 7 — 7 7 7 sodium hydrogencarbonate — — — — 10 — —— filler talc 10 10 10 10 10 10 10 10 Result specific gravity 0.0950.080 0.077 0.085 0.101 0.079 0.817 0.136 expansion ratio (times) 10.312.2 12.8 11.5 9.8 12.5 1.2 7.2 compression set (%) 52 57 58 54 55 50 —80 tear strength (kg/cm) 1.9 1.8 2.0 1.7 1.7 1.9 — 1.7 touch 5 4 4 5 5 51 2 foaming uniformity AA AA A A A AA C A

Examples A7 to A12

[0442] The crosslinked foams obtained in Examples A1 to A6 were shavedtaking into account the configuration of a molding metal mold and thecompression ratio and transferred into the molding metal mold heated at160° C. Pressure of 150 kg/cm² was applied for 11 min at a compressionratio of 1.7 to thereby effect a shaping.

[0443] Immediately after the completion of the above heating underpressure, the molding metal mold with a foam held in its cavity wascooled. Thus, secondarily compressed crosslinked foams were obtained.The properties of the obtained foams are listed in Table 2.

Example A13

[0444] A secondarily compressed crosslinked foam was produced from thecrosslinked foam obtained in Example A1 in the same manner as in ExampleA7, except that pressure was applied at a compression ratio of 2.0. Theproperties of the obtained foam are listed in Table 2.

Comparative Example A3

[0445] A secondarily compressed crosslinked foam was obtained in thesame manner as in Example A7, except that the crosslinked foam obtainedin Comparative Example A2 was used in place of the crosslinked foamobtained in Example A1. The properties of the obtained foam are listedin Table 2. TABLE 2 Example Comp. Ex. A7 A8 A9 A10 A11 A12 A13 A3 Foambefore Foam of Foam of Foam of Foam of Foam of Foam of Foam of Foam ofre-compression Example Example Example Example Example Example ExampleComp. Ex. A2 A1 A2 A3 A4 A5 A6 A1 Compression ratio 1.7 1.7 1.7 1.7 1.71.7 2.0 1.7 Properties of foam after re-compression specific gravity0.15 0.13 0.13 0.14 0.16 0.13 0.19 0.23 compression set (%) 38 42 44 4243 36 27 63 tear strength 2.5 2.7 2.6 2.2 2.3 2.5 3.1 3.1 (kg/cm)

Example A14

[0446] A foam was obtained in the same manner as in Example A1, exceptthat 100 parts by weight of linear ethylene/1-butene copolymer (A-4)having an ethylene content of 89 mol %, a density (ASTM D 1505) of 0.89g/cm³, an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 1.8 g/10 min, an Mw/Mn of 2.5 and a gη* value of1.00 was used in place of the 100 parts by weight of linearethylene/1-butene copolymer (A-1), and talc was not used.

[0447] Thereafter, a secondarily compressed crosslinked foam wasproduced from this foam in the same manner as in Example A7. Theproperties of the obtained foam are listed in Table 3.

Example A15

[0448] A foam was obtained in the same manner as in Example A14, exceptthat 70 parts by weight of linear ethylene/1-butene copolymer (A-4) and30 parts by weight of linear ethylene/1-hexene copolymer (A-5) having anethylene content of 94 mol %, a density (ASTM D 1505) of 0.91 g/cm³, anMFR (measured at 190° C. under a load of 2.16 kg in accordance with ASTMD 1238) of 1.5 g/10 min, an Mw/Mn of 2.1 and a gη* value of 1.00 wereused in place of the 100 parts by weight of linear ethylene/1-butenecopolymer (A-4), and talc was not used.

[0449] Thereafter, a secondarily compressed crosslinked foam wasproduced from this foam in the same manner as in Example A7. Theproperties of the obtained foam are listed in Table 3. TABLE 3 ExampleA14 A15 Formulation of olefin elastomer compsn. (pts. wt.)ethylene/α-olefin copolymer linear ethylene/1-butene copolymer (A-4) 10070 linear ethylene/1-hexane copolymer (A-5) — 30 crosslinking agent DCP0.5 0.5 crosslinking auxiliary TAIC 0.35 0.35 foaming agentazodicarbonamide 7 7 Compression ratio 1.7 1.7 Properties of foam afterre-compression specific gravity 0.14 0.13 compression set (%) 36 37 tearstrength (kg/cm) 2.6 2.9

Example B1

[0450] A mixture consisting of:

[0451] 95 parts by weight of linear ethylene/1-butene copolymer (A-1)having an ethylene content of 91 mol %, a density (ASTM D 1505) of 0.89g/cm³, an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 3.6 g/10 min, an Mw/Mn of 2.1 and a gη* value of1.00;

[0452] 5 parts by weight of modified ethylene/1-butene copolymer (graftamount (in terms of maleic anhydride)=0.5% by weight) obtained bygrafting with maleic anhydride an ethylene/1-butene copolymer having anethylene content of 89 mol %, a density (ASTM D 1505) of 0.89 g/cm³ andan MFR (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 3.6 g/10 min;

[0453] 0.5 part by weight of dicumyl peroxide (DCP);

[0454] 0.35 part by weight (in terms of TAIC contents) of triallylisocyanurate (TAIC) (trade name: M-60 (TAIC content 60%), produced byNippon Kasei Chemical Co., Ltd.);

[0455] 7 parts by weight of azodicarbonamide, and

[0456] 10 parts by weight of talc, was milled by means of rolls whosesurface temperature was set at 120° C. for 10 min, and sheeted.

[0457] The obtained sheet was charged into a press metal mold and heatedunder a pressure of 150 kg/cm² at 160° C. for 12 min. Thus, a foam (24.5mm thickness, 150 mm length and 200 mm width) was obtained.

[0458] The expansion ratio, compression set and tear strength of theobtained foam were measured by the above methods, and the soft touch andfoaming uniformity were evaluated by the above methods. The results aregiven in Table 4.

[0459] The thus obtained crosslinked foam was shaved taking into accountthe configuration of a molding metal mold and the compression ratio andtransferred into the molding metal mold heated at 160° C. Pressure of150 kg/cm² was applied for 10 min at a compression ratio of 1.7 tothereby effect a shaping.

[0460] Immediately after the completion of the above heating underpressure, the molding metal mold with a foam held in its cavity wascooled. Thus, a secondarily compressed crosslinked foam was obtained.The properties of the obtained foam are listed in Table 5.

Example B2

[0461] The same procedure as in Example B1 was repeated except that alinear ethylene/1-butene copolymer (A-4) having an ethylene content of89 mol %, a density (ASTM D 1505) of 0.89 g/cm³, an MFR (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 1.8g/10 min, an Mw/Mn of 2.5 and a gη* value of 1.00 was used in place ofthe linear ethylene/1-butene copolymer (A-1). The results are given inTable 4.

[0462] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B3

[0463] The same procedure as in Example B1 was repeated except that 50parts by weight of a linear ethylene/1-butene copolymer (A-1) and 45parts by weight of a linear ethylene/1-hexene copolymer (A-5) having anethylene content of 94 mol %, a density (ASTM D 1505) of 0.91 g/cm³, anMFR (measured at 190° C. under a load of 2.16 kg in accordance with ASTMD 1238) of 1.5 g/10 min, an Mw/Mn of 2.1 and a gη* value of 1.00 wasused in place of 95 parts by weight of the linear ethylene/1-butenecopolymer (A-1). The results are given in Table 4.

[0464] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B4

[0465] The same procedure as in Example B1 was repeated except that 80parts by weight of the linear ethylene/1-butene copolymer (A-4) as usedin Example B2 and 20 parts by weight of the high-pressure processedlow-density polyethylene having a density (ASTM D 1505) of 0.92 g/cm³and an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 3.0 g/10 min were used in place of 95 parts byweight of the linear ethylene/1-butene copolymer (A-1) and 5 parts byweight of the modified ethylene/1-butene copolymer. The results aregiven in Table 4.

[0466] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B5

[0467] The same procedure as in Example B4 was repeated except that 40parts by weight of the linear ethylene/1-butene copolymer (A-1) as usedin Example B1 and 40 parts by weight of the linear ethylene/1-hexenecopolymer (A-5) as used in Example B3 were used in place of 80 parts byweight of the linear ethylene/1-butene copolymer (A-4). The results aregiven in Table 4.

[0468] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B6

[0469] The same procedure as in Example B4 was repeated except that 75parts by weight of the linear ethylene/1-butene copolymer (A-4) and 5parts by weight of the modified ethylene/1-butene copolymer were used inplace of 80 parts by weight of the linear ethylene/1-butene copolymer(A-4). The results are given in Table 4.

[0470] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B7

[0471] The same procedure as in Example B5 was repeated except that 35parts by weight of the linear ethylene/1-hexene copolymer (A-5) and 5parts by weight of the modified ethylene/1-butene copolymer were used inplace of 40 parts by weight of the linear ethylene/1-hexene copolymer(A-5). The results are given in Table 4.

[0472] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B8

[0473] The same procedure as in Example B1 was repeated except that theamounts of added dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC)were changed to 0.8 part by weight and 0.1 part by weight (in terms ofTAIC contents), respectively. The results are given in Table 4.

[0474] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Example B9

[0475] The same procedure as in Example B1 was repeated except thatlong-chain branched ethylene/1-butene copolymer (A-3) having an ethylenecontent of 89 mol %, a density (ASTM D 1505) of 0.89 g/cm³, an MFR(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 3.6 g/10 min, an Mw/Mn of 1.9 and a gη* value of 0.89 was usedin place of the linear ethylene/1-butene copolymer (A-1). The resultsare given in Table 4.

[0476] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5.

Comparative Example B1

[0477] The same procedure as in Example B1 was repeated except that 100parts by weight of an ethylene/vinyl acetate copolymer (vinyl acetatecontent: 19 % by weight) having a density (ASTM D 1505) of 0.94 g/cm³and an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 2.5 g/10 min was used in place of 95 parts byweight of the linear ethylene/1-butene copolymer (A-1) and 5 parts byweight of the modified etylene/1-butene copolymer. The results are givenin Table 4.

[0478] A secondarily compressed crosslinked foam was produced from thethus obtained crosslinked foam in the same manner as in Example B1. Theproperties of the obtained foam are listed in Table 5. TABLE 4 Comp. Ex.B1 Ex. B2 Ex. B3 Ex. B4 Ex. B5 Ex. B6 Ex. B7 Ex. B8 Ex. B9 Ex. B1Formulation of olefin elastomer compsn. (pts. wt.) ethylene/α-olefincopolymer linear ethylene/1-butene copolymer (A-1) 95 50 40 40 95long-chain branched ethylene/1-butene 95 copolymer (A-3) linearethylene/1-butene copolymer (A-4) 95 80 75 linear ethylene/1-hexenecopolymer (A-5) 45 40 35 modified polyolefin modified ethylene/1-butenecopolymer 5 5 5 5 5 5 5 high-pressure processed low-density polyethyleneethylene homopolymer 20 20 20 20 ethylene/vinyl acetate copolymer 100crosslinking agent DCP 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.8 0.5 0.5crosslinking auxiliary TAIC 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.1 0.350.35 foaming agent azodicarbonamide 7 7 7 7 7 7 7 7 7 7 filler Talc 1010 10 10 10 10 10 10 10 10 Result specific gravity 0.098 0.086 0.0900.086 0.089 0.088 0.091 0.082 0.084 0.136 expansion ratio (times) 10.111.4 10.9 11.4 11.0 11.1 10.8 12.0 11.7 7.2 compression set (%) 55 53 5452 54 54 56 59 54 80 tear strength (kg/cm) 2.0 2.0 2.1 2.0 2.1 2.1 2.22.1 2.0 1.7 touch 5 5 4 5 4 5 4 4 5 2 foaming uniformity AA AA AA AA AAAA AA A AA A

[0479] TABLE 5 Comp. Ex. B1 Ex. B2 Ex. B3 Ex. B4 Ex. B5 Ex. B6 Ex. B7Ex. B8 Ex. B9 Ex. B1 Compression ratio 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.71.7 1.7 Properties of foam after re-compression specific gravity 0.150.13 0.14 0.14 0.14 0.13 0.14 0.13 0.13 0.23 compression set (%) 40 3739 35 41 35 43 43 38 63 tear strength (kg/cm) 2.7 2.8 2.9 2.9 3.0 3.03.2 2.8 2.8 3.1

Example C1

[0480] A mixture consisting of:

[0481] 90 parts by weight of linear ethylene/1-butene copolymer (A-1)having an ethylene content of 91 mol %, a density (ASTM D 1505) of 0.89g/cm³, an MFR (measured at 190° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 3.6 g/10 min and a gη* value of 1.00;

[0482] 10 parts by weight of propylene/ethylene block copolymer(ethylene content=15 mol %) having a density (ASTM D 1505) of 0.91 g/cm³and an MFR (measured at 230° C. under a load of 2.16 kg in accordancewith ASTM D 1238) of 23 g/10 min;

[0483] 0.5 part by weight of dicumyl peroxide (DCP);

[0484] 0.35 part by weight (in terms of TAIC contents) of triallylisocyanurate (TAIC) (trade name: M-60 (TAIC content 60%), produced byNippon Kasei Chemical Co., Ltd.);

[0485] 7 parts by weight of azodicarbonamide; and

[0486] 10 parts by weight of talc, was milled by means of rolls whosesurface temperature was set at 110° C. for 10 min, and sheeted.

[0487] The obtained sheet was charged into a press metal mold and heatedunder a pressure of 150 kg/cm² at 160° C. for 12 min. Thus, a foam (26mm thickness, 163 mm length and 210 mm width) was obtained.

[0488] The expansion ratio, compression set and tear strength of theobtained foam were measured by the above methods, and the soft touch andfoaming uniformity were evaluated by the above methods. The results aregiven in Table 6.

Example C2

[0489] The same procedure as in Example C1 was repeated except that 10parts by weight of propylene homopolymer having a density (ASTM D 1505)of 0.91 g/cm³ and an MFR (measured at 230° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 20 g/10 min was used in place of the 10parts by weight of propylene/ethylene block copolymer. The results aregiven in Table 6.

Example C3

[0490] The same procedure as in Example C1 was repeated except that 10parts by weight of propylene/ethylene random copolymer (propylenecontent: 96 mol %) having a density (ASTM D 1505) of 0.90 g/cm³ and anMFR (measured at 230° C. under a load of 2.16 kg in accordance with ASTMD 1238) of 7 g/10 min was used in place of the 10 parts by weight ofpropylene/ethylene block copolymer. The results are given in Table 6.

Example C4

[0491] The same procedure as in Example C1 was repeated except that 10parts by weight of propylene/1-butene random copolymer (propylenecontent: 75 mol %) having a density (ASTM D 1505) of 0.89 g/cm³ and anMFR (measured at 230° C. under a load of 2.16 kg in accordance with ASTMD 1238) of 6 g/10 min was used in place of the 10 parts by weight ofpropylene/ethylene block copolymer. The results are given in Table 6.

Example C5

[0492] The same procedure as in Example C1 was repeated except that 45parts by weight of linear ethylene/1-butene copolymer (A-1) and 45 partsby weight of ethylene/1-hexene copolymer (A-2) having an ethylenecontent of 95 mol %, a density (ASTM D 1505) of 0.91 g/cm³ and an MFR(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 4.0 g/10 min was used in place of the 90 parts by weight oflinear ethylene/1-butene copolymer (A-1). The results are given in Table6.

Example C6

[0493] The same procedure as in Example C1 was repeated except that theamounts of added dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC)were changed to 0.8 part by weight and 0.1 part by weight (in terms ofTAIC contents), respectively. The results are given in Table 6.

Example C7

[0494] The same procedure as in Example C1 was repeated except that theamounts of added dicumyl peroxide (DCP) and triallyl isocyanurate (TAIC)were changed to 0.2 part by weight and 0.6 part by weight (in terms ofTAIC contents), respectively. The results are given in Table 6.

Example C8

[0495] The same procedure as in Example C1 was repeated except that 10parts by weight of sodium hydrogencarbonate was used in place of theazodicarbonamide. The results are given in Table 6.

Example C9

[0496] The same procedure as in Example C1 was repeated except thatlong-chain branched ethylene/1-butene copolymer (A-3) having an ethylenecontent of 89 mol %, a density (ASTM D 1505) of 0.89 g/cm³, an MFR(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 3.6 g/10 min and a gη* value of 0.89 was used in place of thelinear ethylene/1-butene copolymer (A-1). The results are given in Table6.

Comparative Example C1

[0497] The same procedure as in Example C1 was repeated except that thetriallyl isocyanurate (TAIC) was not used. The results are given inTable 6.

Comparative Example C2

[0498] The same procedure as in Example C1 was repeated except that anethylene/vinyl acetate copolymer (vinyl acetate content: 19% by weight)having a density (ASTM D 1505) of 0.94 g/cm³ and an MFR (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 2.5g/10 min was used in place of the linear ethylene/1-butene copolymer(A-1). The results are given in Table 6. TABLE 6 Example C1 C2 C3 C4 C5C6 C7 C8 Formulation of olefin elastomer compsn. (pts. wt.)ethylene/α-olefin copolymer linear ethylene/1-butene copolymer (A-1) 9090 90 90 45 90 90 90 linear ethylene/1-hexene copolymer (A-2) — — — — 45— — — polypropylene propylene/ethylene block copolymer 10 — — — 10 10 1010 propylene homopolymer — 10 — — — — — — propylene/ethylene randomcopolymer — — 10 — — — — — propylene/1-butene random copolymer — — — 10— — — — crosslinking agent DCP 0.5 0.5 0.5 0.5 0.5 0.8 0.2 0.5crosslinking auxiliary TAIC 0.35 0.35 0.35 0.35 0.35 0.1 0.6 0.35foaming agent azodicarbonamide 7 7 7 7 7 7 7 — sodium hydrogencarbonate— — — — — — — 10 filler talc 10 10 10 10 10 10 10 10 Result expansionratio (times) 12.5 13.0 12.7 12.8 11.6 9.8 13.5 10.5 compression set (%)57 58 56 56 57 59 56 56 tear strength (kg/cm) 1.7 1.7 1.8 1.8 1.7 2.01.7 1.7 touch 5 4 5 5 4 4 5 5 foaming uniformity AA A AA AA A A A A Ex.Comp. Ex. C9 C1 C2 Formulation of olefin elastomer compsn. (pts. wt.)ethylene/α-olefin copolymer linear ethylene/1-butene — 90 — copolymer(A-1) long-chain branched ethylene/1-butene 90 — — copolymer (A-3)ethylene/vinyl acetate copolymer — — 100 polypropylenepropylene/ethylene block copolymer 10 10 — crosslinking agent DCP 0.50.5 0.5 crosslinking auxiliary TAIC 0.35 0 0.35 foaming agentazodicarbonamide 7 7 7 sodium hydrogencarbonate — — — filler talc 10 1010 Result expansion ratio (times) 13.1 1.3 7.2 compression set (%) 55 —80 tear strength (kg/cm) 1.9 — 1.7 touch 5 1 2 foaming uniformity AA C A

What is claimed is:
 1. A crosslinked olefin elastomer foam having aspecific gravity of 0.05 to 0.2, an expansion ratio of 8 to 15, acompression set of 30 to 60% and a tear strength of 1.5 to 2.5 kg/cm. 2.A crosslinked olefin elastomer foam having a specific gravity of 0.1 to0.2, a compression set of 20 to 60% and a tear strength of 2.0 to 4.0kg/cm.
 3. The crosslinked olefin elastomer foam as claimed in claim 1 or2, which is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising: anethylene/α-olefin copolymer (A) having a density of 0.88 to 0.92 g/cm³and a melt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 10 g/10 min; an organic peroxide(D); a crosslinking auxiliary (E); and a foaming agent (F).
 4. Thecrosslinked olefin elastomer foam as claimed in claim 3, wherein theethylene/α-olefin copolymer (A) has a molecular weight distribution(Mw/Mn), as measured by gel permeation chromatography (GPC), of 2.3 to4.0.
 5. The crosslinked olefin elastomer foam as claimed in claim 3,wherein the ethylene/α-olefin copolymer (A) comprises a mixture of: 5 to95 parts by weight of an ethylene/α-olefin copolymer (A1) having adensity of greater than 0.88 g/cm³ but not greater than 0.90 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min; and 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A2) having a density of 0.90to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, providedthat the sum of ethylene/α-olefin copolymer (A1) and ethylene/α-olefincopolymer (A2) is 100 parts by weight, the mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.
 6. The crosslinked olefin elastomerfoam as claimed in claim 3, wherein the ethylene/α-olefin copolymer (A)comprises a mixture of: 5 to 95 parts by weight of an ethylene/α-olefincopolymer (A3) having a density of 0.88 to less than 0.91 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min; and 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A4) having a density of 0.91to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, providedthat the sum of ethylene/α-olefin copolymer (A3) and ethylene/α-olefincopolymer (A4) is 100 parts by weight, the mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.
 7. The crosslinked olefin elastomerfoam as claimed in claim 3, wherein the crosslinking auxiliary (E) andthe organic peroxide (D) are used in a weight ratio ((E)/(D)) of 1/8 to3/1.
 8. An elastomer composition for crosslinked olefin elastomer foam,comprising: an ethylene/α-olefin copolymer (A) having a density of 0.88to 0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min; anorganic peroxide (D); a crosslinking auxiliary (E); and a foaming agent(F).
 9. The elastomer composition for crosslinked olefin elastomer foamas claimed in claim 8, wherein the ethylene/α-olefin copolymer (A) has amolecular weight distribution (Mw/Mn), as measured by gel permeationchromatography (GPC), of 2.3 to 4.0.
 10. An elastomer composition forcrosslinked olefin elastomer foam, comprising: an ethylene/α-olefincopolymer (A) having a density of 0.88 to 0.92 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 10 g/10 min; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (A) comprises a mixture of: 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A1) having a density ofgreater than 0.88 g/cm³ but not greater than 0.90 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 50 g/10 min; and 5 to 95 parts by weight of anethylene/α-olefin copolymer (A2) having a density of 0.90 to 0.93 g/cm³and a melt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1) and ethylene/α-olefin copolymer(A2) is 100 parts by weight, the mixture having a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.5 to 10 g/10 min.
 11. An elastomer composition forcrosslinked olefin elastomer foam, comprising: an ethylene/α-olefincopolymer (A) having a density of 0.88 to 0.92 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 10 g/10 min; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (A) comprises a mixture of: 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A3) having a density of 0.88to less than 0.91 g/cm³ and a melt flow rate (measured at 190° C. undera load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min;and 5 to 95 parts by weight of an ethylene/α-olefin copolymer (A4)having a density of 0.91 to 0.93 g/cm³ and a melt flow rate (measured at190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A3) and ethylene/α-olefin copolymer (A4) is 100 parts by weight, themixture having a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.5 to 10 g/10 min.
 12. Theelastomer composition for crosslinked olefin elastomer foam as claimedin any of claims 8, 10 and 11, wherein the crosslinking auxiliary (E)and the organic peroxide (D) are used in a weight ratio ((E)/(D)) of 1/8to 3/1.
 13. A crosslinked olefin elastomer foam, which is a crosslinkedfoam obtained by heating an olefin elastomer composition, the olefinelastomer composition comprising: 70 to 95 parts by weight of anethylene/α-olefin copolymer (A) having a density of 0.88 to 0.92 g/cm³and a melt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 10 g/10 min, and 5 to 30 parts byweight of a modified polyolefin (B) obtained by grafting a polyolefinwith an unsaturated carboxylic acid or a derivative thereof, providedthat the sum of ethylene/α-olefin copolymer (A) and modified polyolefin(B) is 100 parts by weight; an organic peroxide (D); a crosslinkingauxiliary (E); and a foaming agent (F).
 14. The crosslinked olefinelastomer foam as claimed in claim 13, wherein the ethylene/α-olefincopolymer (A) has a molecular weight distribution (Mw/Mn), as measuredby gel permeation chromatography (GPC), of 2.3 to 4.0.
 15. Thecrosslinked olefin elastomer foam as claimed in claim 13, wherein theethylene/α-olefin copolymer (A) comprises a mixture of: 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A1) having a density ofgreater than 0.88 g/cm³ but not greater than 0.90 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 50 g/10 min, and 5 to 95 parts by weight of anethylene/α-olefin copolymer (A2) having a density of 0.90 to 0.93 g/cm³and a melt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1) and ethylene/α-olefin copolymer(A2) is 100 parts by weight, the mixture having a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.5 to 10 g/10 min.
 16. A crosslinked olefin elastomer foam,which is a crosslinked foam obtained by heating an olefin elastomercomposition, the olefin elastomer composition comprising: 50 to 95 partsby weight of an ethylene/α-olefin copolymer (A) having a density of 0.88to 0.92 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min, and 5 to50 parts by weight of a high-pressure processed low-density polyethylene(C) having a density of 0.91 to less than 0.93 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 50 g/10 min, provided that the sum ofethylene/α-olefin copolymer (A) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F).
 17. A crosslinkedolefin elastomer foam, which is a crosslinked foam obtained by heatingan olefin elastomer composition, the olefin elastomer compositioncomprising: 5 to 90 parts by weight of an ethylene/α-olefin copolymer(A1) having a density of greater than 0.88 g/cm³ but not greater than0.90 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, 5 to 90parts by weight of an ethylene/α-olefin copolymer (A2) having a densityof 0.90 to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min,and 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2) and high-pressure processed low-density polyethylene (C) is 100parts by weight; an organic peroxide (D); a crosslinking auxiliary (E);and a foaming agent (F), wherein the ethylene/α-olefin copolymer (A1)and the ethylene/α-olefin copolymer (A2) constitute a mixture having amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.5 to 10 g/10 min.
 18. A crosslinkedolefin elastomer foam, which is a crosslinked foam obtained by heatingan olefin elastomer composition, the olefin elastomer compositioncomprising: 20 to 90 parts by weight of an ethylene/α-olefin copolymer(A) having a density of 0.88 to 0.92 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 10 g/10 min, 5 to 30 parts by weight of a modifiedpolyolefin (B) obtained by grafting a polyolefin with an unsaturatedcarboxylic acid or a derivative thereof, and 5 to 50 parts by weight ofa high-pressure processed low-density polyethylene (C) having a densityof 0.91 to less than 0.93 g/cm³ and a melt flow rate (measured at 190°C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50g/10 min, provided that the sum of ethylene/α-olefin copolymer (A),modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F).
 19. A crosslinkedolefin elastomer foam, which is a crosslinked foam obtained by heatingan olefin elastomer composition, the olefin elastomer compositioncomprising: 5 to 85 parts by weight of an ethylene/α-olefin copolymer(A1) having a density of greater than 0.88 g/cm³ but not greater than0.90 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, 5 to 85parts by weight of an ethylene/α-olefin copolymer (A2) having a densityof 0.90 to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under aload of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, 5to 30 parts by weight of a modified polyolefin (B) obtained by graftinga polyolefin with an unsaturated carboxylic acid or a derivativethereof, and 5 to 50 parts by weight of a high-pressure processedlow-density polyethylene (C) having a density of 0.91 to less than 0.93g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (A1) and the ethylene/α-olefin copolymer(A2) constitute a mixture having a melt flow rate (measured at 190° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10g/10 min.
 20. The crosslinked olefin elastomer foam as claimed in any ofclaims 13, 16, 17, 18 and 19, wherein the crosslinking auxiliary (E) andthe organic peroxide (D) are used in a weight ratio ((E)/(D)) of 1/8 to3/1.
 21. An elastomer composition for crosslinked olefin elastomer foam,comprising: 70 to 95 parts by weight of an ethylene/α-olefin copolymer(A) having a density of 0.88 to 0.92 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 10 g/10 min, and 5 to 30 parts by weight of a modifiedpolyolefin (B) obtained by grafting a polyolefin with an unsaturatedcarboxylic acid or a derivative thereof, provided that the sum ofethylene/α-olefin copolymer (A) and modified polyolefin (B) is 100 partsby weight; an organic peroxide (D); a crosslinking auxiliary (E); and afoaming agent (F).
 22. The elastomer composition for crosslinked olefinelastomer foam as claimed in claim 21, wherein the ethylene/α-olefincopolymer (A) has a molecular weight distribution (Mw/Mn), as measuredby gel permeation chromatography (GPC), of 2.3 to 4.0.
 23. The elastomercomposition for crosslinked olefin elastomer foam as claimed in claim21, wherein the ethylene/α-olefin copolymer (A) comprises a mixture of:5 to 95 parts by weight of an ethylene/α-olefin copolymer (A1) having adensity of greater than 0.88 g/cm³ but not greater than 0.90 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, and 5 to 95 parts byweight of an ethylene/α-olefin copolymer (A2) having a density of 0.90to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, providedthat the sum of ethylene/α-olefin copolymer (A1) and ethylene/α-olefincopolymer (A2) is 100 parts by weight, the mixture having a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.5 to 10 g/10 min.
 24. An elastomer composition forcrosslinked olefin elastomer foam, comprising: 50 to 95 parts by weightof an ethylene/α-olefin copolymer (A) having a density of 0.88 to 0.92g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 10 g/10 min, and 5 to 50 partsby weight of a high-pressure processed low-density polyethylene (C)having a density of 0.91 to less than 0.93 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 50 g/10 min, provided that the sum of ethylene/α-olefincopolymer (A) and high-pressure processed low-density polyethylene (C)is 100 parts by weight; an organic peroxide (D); a crosslinkingauxiliary (E); and a foaming agent (F).
 25. An elastomer composition forcrosslinked olefin elastomer foam, comprising: 5 to 90 parts by weightof an ethylene/α-olefin copolymer (A1) having a density of greater than0.88 g/cm³ but not greater than 0.90 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 50 g/10 min, 5 to 90 parts by weight of anethylene/α-olefin copolymer (A2) having a density of 0.90 to 0.93 g/cm³and a melt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, and 5 to 50 parts byweight of a high-pressure processed low-density polyethylene (C) havinga density of 0.91 to less than 0.93 g/cm³ and a melt flow rate (measuredat 190° C. under a load of 2.16 kg in accordance with ASTM D 1238) of0.1 to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer(A1), ethylene/α-olefin copolymer (A2) and high-pressure processedlow-density polyethylene (C) is 100 parts by weight; an organic peroxide(D); a crosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (A1) and the ethylene/α-olefin copolymer(A2) constitute a mixture having a melt flow rate (measured at 190° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10g/10 min.
 26. An elastomer composition for crosslinked olefin elastomerfoam, comprising: 20 to 90 parts by weight of an ethylene/α-olefincopolymer (A) having a density of 0.88 to 0.92 g/cm³ and a melt flowrate (measured at 190° C. under a load of 2.16 kg in accordance withASTM D 1238) of 0.1 to 10 g/10 min, 5 to 30 parts by weight of amodified polyolefin (B) obtained by grafting a polyolefin with anunsaturated carboxylic acid or a derivative thereof, and 5 to 50 partsby weight of a high-pressure processed low-density polyethylene (C)having a density of 0.91 to less than 0.93 g/cm³ and a melt flow rate(measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 50 g/10 min, provided that the sum of ethylene/α-olefincopolymer (A), modified polyolefin (B) and high-pressure processedlow-density polyethylene (C) is 100 parts by weight; an organic peroxide(D); a crosslinking auxiliary (E); and a foaming agent (F).
 27. Anelastomer composition for crosslinked olefin elastomer foam, comprising:5 to 85 parts by weight of an ethylene/α-olefin copolymer (A1) having adensity of greater than 0.88 g/cm³ but not greater than 0.90 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, 5 to 85 parts byweight of an ethylene/α-olefin copolymer (A2) having a density of 0.90to 0.93 g/cm³ and a melt flow rate (measured at 190° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 50 g/10 min, 5 to 30parts by weight of a modified polyolefin (B) obtained by grafting apolyolefin with an unsaturated carboxylic acid or a derivative thereof,and 5 to 50 parts by weight of a high-pressure processed low-densitypolyethylene (C) having a density of 0.91 to less than 0.93 g/cm³ and amelt flow rate (measured at 190° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.1 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (A1), ethylene/α-olefin copolymer(A2), modified polyolefin (B) and high-pressure processed low-densitypolyethylene (C) is 100 parts by weight; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (A1) and the ethylene/α-olefin copolymer(A2) constitute a mixture having a melt flow rate (measured at 190° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.5 to 10g/10 min.
 28. The elastomer composition for crosslinked olefin elastomerfoam as claimed in any of claims 21, 24, 25, 26 and 27, wherein thecrosslinking auxiliary (E) and the organic peroxide (D) are used in aweight ratio ((E)/(D)) of 1/8 to 3/1.
 29. A crosslinked olefin elastomerfoam, which is a crosslinked foam obtained by heating an olefinelastomer composition, the olefin elastomer composition comprising: 70to 98 parts by weight of an ethylene/α-olefin copolymer (G) having adensity of 0.88 to 0.92 g/cm³ and a melt flow rate (measured at 190° C.under a load of 2.16 kg in accordance with ASTM D 1238) of 0.1 to 50g/10 min, and 2 to 30 parts by weight of a polypropylene (H) having amelt flow rate (measured at 230° C. under a load of 2.16 kg inaccordance with ASTM D 1238) of 0.5 to 50 g/10 min, provided that thesum of ethylene/α-olefin copolymer (G) and polypropylene (H) is 100parts by weight; an organic peroxide (D); a crosslinking auxiliary (E);and a foaming agent (F), wherein the ethylene/α-olefin copolymer (G) andthe polypropylene (H) constitute a mixture having a melt flow rate(measured at 230° C. under a load of 2.16 kg in accordance with ASTM D1238) of 0.1 to 10 g/10 min.
 30. The crosslinked olefin elastomer foamas claimed in claim 29, wherein the polypropylene (H) is at least onemember selected from the group consisting of propylene homopolymer,propylene block copolymers and propylene/α-olefin random copolymers. 31.The crosslinked olefin elastomer foam as claimed in claim 29, whereinthe crosslinking auxiliary (E) and the organic peroxide (D) are used ina weight ratio ((E)/(D)) of 1/8 to 3/1.
 32. An elastomer composition forcrosslinked olefin elastomer foam, comprising: 70 to 98 parts by weightof an ethylene/α-olefin copolymer (G) having a density of 0.88 to 0.92g/cm³ and a melt flow rate (measured at 190° C. under a load of 2.16 kgin accordance with ASTM D 1238) of 0.1 to 50 g/10 min, and 2 to 30 partsby weight of a polypropylene (H) having a melt flow rate (measured at230° C. under a load of 2.16 kg in accordance with ASTM D 1238) of 0.5to 50 g/10 min, provided that the sum of ethylene/α-olefin copolymer (G)and polypropylene (H) is 100 parts by weight; an organic peroxide (D); acrosslinking auxiliary (E); and a foaming agent (F), wherein theethylene/α-olefin copolymer (G) and the polypropylene (H) constitute amixture having a melt flow rate (measured at 230° C. under a load of2.16 kg in accordance with ASTM D 1238) of 0.1 to 10 g/10 min.
 33. Theelastomer composition for crosslinked olefin elastomer foam as claimedin claim 32, wherein the polypropylene (H) is at least one memberselected from the group consisting of propylene homopolymer, propyleneblock copolymers and propylene/α-olefin random copolymers.
 34. Theelastomer composition for crosslinked olefin elastomer foam as claimedin claim 32, wherein the crosslinking auxiliary (E) and the organicperoxide (D) are used in a weight ratio ((E)/(D)) of 1/8 to 3/1.